diff --git a/docs/builtin-tools.md b/docs/builtin-tools.md
index c61fa8b51d..86f41b5c60 100644
--- a/docs/builtin-tools.md
+++ b/docs/builtin-tools.md
@@ -20,6 +20,47 @@ These tools are passed to the agent via the `builtin_tools` parameter and are ex
 
     If a provider supports a built-in tool that is not currently supported by Pydantic AI, please file an issue.
 
+## Dynamic Configuration
+
+Sometimes you need to configure a built-in tool dynamically based on the [run context][pydantic_ai.tools.RunContext] (e.g., user dependencies), or conditionally omit it. You can achieve this by passing a function to `builtin_tools` that takes [`RunContext`][pydantic_ai.tools.RunContext] as an argument and returns an [`AbstractBuiltinTool`][pydantic_ai.builtin_tools.AbstractBuiltinTool] or `None`.
+
+This is particularly useful for tools like [`WebSearchTool`][pydantic_ai.builtin_tools.WebSearchTool] where you might want to set the user's location based on the current request, or disable the tool if the user provides no location.
+
+```python {title="dynamic_builtin_tool.py"}
+from pydantic_ai import Agent, RunContext, WebSearchTool
+
+
+async def prepared_web_search(ctx: RunContext[dict]) -> WebSearchTool | None:
+    if not ctx.deps.get('location'):
+        return None
+
+    return WebSearchTool(
+        user_location={'city': ctx.deps['location']},
+    )
+
+agent = Agent(
+    'openai-responses:gpt-5',
+    builtin_tools=[prepared_web_search],
+    deps_type=dict,
+)
+
+# Run with location
+result = agent.run_sync(
+    'What is the weather like?',
+    deps={'location': 'London'},
+)
+print(result.output)
+#> It's currently raining in London.
+
+# Run without location (tool will be omitted)
+result = agent.run_sync(
+    'What is the capital of France?',
+    deps={'location': None},
+)
+print(result.output)
+#> The capital of France is Paris.
+```
+
 ## Web Search Tool
 
 The [`WebSearchTool`][pydantic_ai.builtin_tools.WebSearchTool] allows your agent to search the web,
diff --git a/pydantic_ai_slim/pydantic_ai/_agent_graph.py b/pydantic_ai_slim/pydantic_ai/_agent_graph.py
index 6a14f8b350..043c27c4f5 100644
--- a/pydantic_ai_slim/pydantic_ai/_agent_graph.py
+++ b/pydantic_ai_slim/pydantic_ai/_agent_graph.py
@@ -30,6 +30,7 @@
 from .output import OutputDataT, OutputSpec
 from .settings import ModelSettings
 from .tools import (
+    BuiltinToolFunc,
     DeferredToolCallResult,
     DeferredToolResult,
     DeferredToolResults,
@@ -148,7 +149,7 @@ class GraphAgentDeps(Generic[DepsT, OutputDataT]):
 
     history_processors: Sequence[HistoryProcessor[DepsT]]
 
-    builtin_tools: list[AbstractBuiltinTool] = dataclasses.field(repr=False)
+    builtin_tools: list[AbstractBuiltinTool | BuiltinToolFunc[DepsT]] = dataclasses.field(repr=False)
     tool_manager: ToolManager[DepsT]
 
     tracer: Tracer
@@ -395,9 +396,23 @@ async def _prepare_request_parameters(
         else:
             function_tools.append(tool_def)
 
+    # resolve dynamic builtin tools
+    builtin_tools: list[AbstractBuiltinTool] = []
+    if ctx.deps.builtin_tools:
+        run_context = build_run_context(ctx)
+        for tool in ctx.deps.builtin_tools:
+            if isinstance(tool, AbstractBuiltinTool):
+                builtin_tools.append(tool)
+            else:
+                t = tool(run_context)
+                if inspect.isawaitable(t):
+                    t = await t
+                if t is not None:
+                    builtin_tools.append(t)
+
     return models.ModelRequestParameters(
         function_tools=function_tools,
-        builtin_tools=ctx.deps.builtin_tools,
+        builtin_tools=builtin_tools,
         output_mode=output_schema.mode,
         output_tools=output_tools,
         output_object=output_schema.object_def,
diff --git a/pydantic_ai_slim/pydantic_ai/agent/__init__.py b/pydantic_ai_slim/pydantic_ai/agent/__init__.py
index c8208ac9e6..19edb4a619 100644
--- a/pydantic_ai_slim/pydantic_ai/agent/__init__.py
+++ b/pydantic_ai_slim/pydantic_ai/agent/__init__.py
@@ -43,6 +43,7 @@
 from ..settings import ModelSettings, merge_model_settings
 from ..tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     DocstringFormat,
     GenerateToolJsonSchema,
@@ -170,7 +171,7 @@ def __init__(
         validation_context: Any | Callable[[RunContext[AgentDepsT]], Any] = None,
         output_retries: int | None = None,
         tools: Sequence[Tool[AgentDepsT] | ToolFuncEither[AgentDepsT, ...]] = (),
-        builtin_tools: Sequence[AbstractBuiltinTool] = (),
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] = (),
         prepare_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         prepare_output_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         toolsets: Sequence[AbstractToolset[AgentDepsT] | ToolsetFunc[AgentDepsT]] | None = None,
@@ -197,7 +198,7 @@ def __init__(
         validation_context: Any | Callable[[RunContext[AgentDepsT]], Any] = None,
         output_retries: int | None = None,
         tools: Sequence[Tool[AgentDepsT] | ToolFuncEither[AgentDepsT, ...]] = (),
-        builtin_tools: Sequence[AbstractBuiltinTool] = (),
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] = (),
         prepare_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         prepare_output_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         mcp_servers: Sequence[MCPServer] = (),
@@ -222,7 +223,7 @@ def __init__(
         validation_context: Any | Callable[[RunContext[AgentDepsT]], Any] = None,
         output_retries: int | None = None,
         tools: Sequence[Tool[AgentDepsT] | ToolFuncEither[AgentDepsT, ...]] = (),
-        builtin_tools: Sequence[AbstractBuiltinTool] = (),
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] = (),
         prepare_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         prepare_output_tools: ToolsPrepareFunc[AgentDepsT] | None = None,
         toolsets: Sequence[AbstractToolset[AgentDepsT] | ToolsetFunc[AgentDepsT]] | None = None,
@@ -427,7 +428,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
 
     @overload
@@ -446,7 +447,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
     @asynccontextmanager
@@ -465,7 +466,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
 
diff --git a/pydantic_ai_slim/pydantic_ai/agent/abstract.py b/pydantic_ai_slim/pydantic_ai/agent/abstract.py
index 567b61dff6..96d4d23766 100644
--- a/pydantic_ai_slim/pydantic_ai/agent/abstract.py
+++ b/pydantic_ai_slim/pydantic_ai/agent/abstract.py
@@ -31,6 +31,7 @@
 from ..settings import ModelSettings
 from ..tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     RunContext,
     Tool,
@@ -138,7 +139,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -158,7 +159,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -177,7 +178,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[Any]:
         """Run the agent with a user prompt in async mode.
@@ -262,7 +263,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -282,7 +283,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -301,7 +302,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[Any]:
         """Synchronously run the agent with a user prompt.
@@ -378,7 +379,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[result.StreamedRunResult[AgentDepsT, OutputDataT]]: ...
 
@@ -398,7 +399,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[result.StreamedRunResult[AgentDepsT, RunOutputDataT]]: ...
 
@@ -418,7 +419,7 @@ async def run_stream(  # noqa: C901
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AsyncIterator[result.StreamedRunResult[AgentDepsT, Any]]:
         """Run the agent with a user prompt in async streaming mode.
@@ -610,7 +611,7 @@ def run_stream_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> result.StreamedRunResultSync[AgentDepsT, OutputDataT]: ...
 
@@ -647,7 +648,7 @@ def run_stream_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> result.StreamedRunResultSync[AgentDepsT, Any]:
         """Run the agent with a user prompt in sync streaming mode.
@@ -738,7 +739,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[OutputDataT]]: ...
 
     @overload
@@ -757,7 +758,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[RunOutputDataT]]: ...
 
     def run_stream_events(
@@ -775,7 +776,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[Any]]:
         """Run the agent with a user prompt in async mode and stream events from the run.
 
@@ -866,7 +867,7 @@ async def _run_stream_events(
         usage_limits: _usage.UsageLimits | None = None,
         usage: _usage.RunUsage | None = None,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[Any]]:
         send_stream, receive_stream = anyio.create_memory_object_stream[
             _messages.AgentStreamEvent | AgentRunResultEvent[Any]
@@ -922,7 +923,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
 
     @overload
@@ -941,7 +942,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
     @asynccontextmanager
@@ -961,7 +962,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
 
diff --git a/pydantic_ai_slim/pydantic_ai/agent/wrapper.py b/pydantic_ai_slim/pydantic_ai/agent/wrapper.py
index 38e832fa2b..6e275b3f50 100644
--- a/pydantic_ai_slim/pydantic_ai/agent/wrapper.py
+++ b/pydantic_ai_slim/pydantic_ai/agent/wrapper.py
@@ -16,6 +16,7 @@
 from ..settings import ModelSettings
 from ..tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     Tool,
     ToolFuncEither,
@@ -83,7 +84,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
 
     @overload
@@ -102,7 +103,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
     @asynccontextmanager
@@ -121,7 +122,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
 
diff --git a/pydantic_ai_slim/pydantic_ai/durable_exec/dbos/_agent.py b/pydantic_ai_slim/pydantic_ai/durable_exec/dbos/_agent.py
index ff6730f220..c5adf5221d 100644
--- a/pydantic_ai_slim/pydantic_ai/durable_exec/dbos/_agent.py
+++ b/pydantic_ai_slim/pydantic_ai/durable_exec/dbos/_agent.py
@@ -25,6 +25,7 @@
 from pydantic_ai.settings import ModelSettings
 from pydantic_ai.tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     RunContext,
     Tool,
@@ -138,7 +139,7 @@ async def wrapped_run_workflow(
             usage: _usage.RunUsage | None = None,
             infer_name: bool = True,
             toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-            builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+            builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
             event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
             **_deprecated_kwargs: Never,
         ) -> AgentRunResult[Any]:
@@ -179,7 +180,7 @@ def wrapped_run_sync_workflow(
             usage: _usage.RunUsage | None = None,
             infer_name: bool = True,
             toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-            builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+            builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
             event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
             **_deprecated_kwargs: Never,
         ) -> AgentRunResult[Any]:
@@ -271,7 +272,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -291,7 +292,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -310,7 +311,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -389,7 +390,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -409,7 +410,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -428,7 +429,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -506,7 +507,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, OutputDataT]]: ...
 
@@ -526,7 +527,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, RunOutputDataT]]: ...
 
@@ -546,7 +547,7 @@ async def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AsyncIterator[StreamedRunResult[AgentDepsT, Any]]:
@@ -625,7 +626,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[OutputDataT]]: ...
 
     @overload
@@ -644,7 +645,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[RunOutputDataT]]: ...
 
     def run_stream_events(
@@ -662,7 +663,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[Any]]:
         """Run the agent with a user prompt in async mode and stream events from the run.
 
@@ -739,7 +740,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
 
@@ -759,7 +760,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
@@ -779,7 +780,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
diff --git a/pydantic_ai_slim/pydantic_ai/durable_exec/prefect/_agent.py b/pydantic_ai_slim/pydantic_ai/durable_exec/prefect/_agent.py
index 8b1b6af44a..60c8122686 100644
--- a/pydantic_ai_slim/pydantic_ai/durable_exec/prefect/_agent.py
+++ b/pydantic_ai_slim/pydantic_ai/durable_exec/prefect/_agent.py
@@ -28,6 +28,7 @@
 from pydantic_ai.settings import ModelSettings
 from pydantic_ai.tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     RunContext,
     Tool,
@@ -187,7 +188,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -207,7 +208,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -226,7 +227,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -311,7 +312,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -331,7 +332,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -350,7 +351,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -437,7 +438,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, OutputDataT]]: ...
 
@@ -457,7 +458,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, RunOutputDataT]]: ...
 
@@ -477,7 +478,7 @@ async def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AsyncIterator[StreamedRunResult[AgentDepsT, Any]]:
@@ -556,7 +557,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[OutputDataT]]: ...
 
     @overload
@@ -575,7 +576,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[RunOutputDataT]]: ...
 
     def run_stream_events(
@@ -593,7 +594,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[Any]]:
         """Run the agent with a user prompt in async mode and stream events from the run.
 
@@ -687,7 +688,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
 
     @overload
@@ -706,7 +707,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
     @asynccontextmanager
@@ -725,7 +726,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
 
diff --git a/pydantic_ai_slim/pydantic_ai/durable_exec/temporal/_agent.py b/pydantic_ai_slim/pydantic_ai/durable_exec/temporal/_agent.py
index 6e964c8d08..42fc2a872e 100644
--- a/pydantic_ai_slim/pydantic_ai/durable_exec/temporal/_agent.py
+++ b/pydantic_ai_slim/pydantic_ai/durable_exec/temporal/_agent.py
@@ -33,6 +33,7 @@
 from pydantic_ai.settings import ModelSettings
 from pydantic_ai.tools import (
     AgentDepsT,
+    BuiltinToolFunc,
     DeferredToolResults,
     RunContext,
     Tool,
@@ -270,7 +271,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -290,7 +291,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -309,7 +310,7 @@ async def run(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -390,7 +391,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[OutputDataT]: ...
 
@@ -410,7 +411,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AgentRunResult[RunOutputDataT]: ...
 
@@ -429,7 +430,7 @@ def run_sync(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AgentRunResult[Any]:
@@ -508,7 +509,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, OutputDataT]]: ...
 
@@ -528,7 +529,7 @@ def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
     ) -> AbstractAsyncContextManager[StreamedRunResult[AgentDepsT, RunOutputDataT]]: ...
 
@@ -548,7 +549,7 @@ async def run_stream(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         event_stream_handler: EventStreamHandler[AgentDepsT] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AsyncIterator[StreamedRunResult[AgentDepsT, Any]]:
@@ -627,7 +628,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[OutputDataT]]: ...
 
     @overload
@@ -646,7 +647,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[RunOutputDataT]]: ...
 
     def run_stream_events(
@@ -664,7 +665,7 @@ def run_stream_events(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
     ) -> AsyncIterator[_messages.AgentStreamEvent | AgentRunResultEvent[Any]]:
         """Run the agent with a user prompt in async mode and stream events from the run.
 
@@ -757,7 +758,7 @@ def iter(
         usage_limits: _usage.UsageLimits | None = None,
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, OutputDataT]]: ...
@@ -778,7 +779,7 @@ def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AbstractAsyncContextManager[AgentRun[AgentDepsT, RunOutputDataT]]: ...
 
@@ -798,7 +799,7 @@ async def iter(
         usage: _usage.RunUsage | None = None,
         infer_name: bool = True,
         toolsets: Sequence[AbstractToolset[AgentDepsT]] | None = None,
-        builtin_tools: Sequence[AbstractBuiltinTool] | None = None,
+        builtin_tools: Sequence[AbstractBuiltinTool | BuiltinToolFunc[AgentDepsT]] | None = None,
         **_deprecated_kwargs: Never,
     ) -> AsyncIterator[AgentRun[AgentDepsT, Any]]:
         """A contextmanager which can be used to iterate over the agent graph's nodes as they are executed.
diff --git a/pydantic_ai_slim/pydantic_ai/tools.py b/pydantic_ai_slim/pydantic_ai/tools.py
index e54b829bfb..dcd860b019 100644
--- a/pydantic_ai_slim/pydantic_ai/tools.py
+++ b/pydantic_ai_slim/pydantic_ai/tools.py
@@ -11,6 +11,7 @@
 
 from . import _function_schema, _utils
 from ._run_context import AgentDepsT, RunContext
+from .builtin_tools import AbstractBuiltinTool
 from .exceptions import ModelRetry
 from .messages import RetryPromptPart, ToolCallPart, ToolReturn
 
@@ -25,6 +26,7 @@
     'ToolParams',
     'ToolPrepareFunc',
     'ToolsPrepareFunc',
+    'BuiltinToolFunc',
     'Tool',
     'ObjectJsonSchema',
     'ToolDefinition',
@@ -122,6 +124,15 @@ async def turn_on_strict_if_openai(
 Usage `ToolsPrepareFunc[AgentDepsT]`.
 """
 
+BuiltinToolFunc: TypeAlias = Callable[
+    [RunContext[AgentDepsT]], Awaitable[AbstractBuiltinTool | None] | AbstractBuiltinTool | None
+]
+"""Definition of a function that can prepare a builtin tool at call time.
+
+This is useful if you want to customize the builtin tool based on the run context (e.g. user dependencies),
+or omit it completely from a step.
+"""
+
 DocstringFormat: TypeAlias = Literal['google', 'numpy', 'sphinx', 'auto']
 """Supported docstring formats.
 
diff --git a/tests/test_agent.py b/tests/test_agent.py
index c912334434..9c44f4adfb 100644
--- a/tests/test_agent.py
+++ b/tests/test_agent.py
@@ -57,7 +57,12 @@
     TextOutput,
 )
 from pydantic_ai.agent import AgentRunResult, WrapperAgent
-from pydantic_ai.builtin_tools import CodeExecutionTool, MCPServerTool, WebSearchTool
+from pydantic_ai.builtin_tools import (
+    CodeExecutionTool,
+    MCPServerTool,
+    WebSearchTool,
+    WebSearchUserLocation,
+)
 from pydantic_ai.models.function import AgentInfo, DeltaToolCall, DeltaToolCalls, FunctionModel
 from pydantic_ai.models.test import TestModel
 from pydantic_ai.output import OutputObjectDefinition, StructuredDict, ToolOutput
@@ -6313,3 +6318,115 @@ def llm(messages: list[ModelMessage], _info: AgentInfo) -> ModelResponse:
             ]
         )
         assert run.all_messages_json().startswith(b'[{"parts":[{"content":"Hello",')
+
+
+@dataclass
+class UserContext:
+    location: str | None
+
+
+async def prepared_web_search(ctx: RunContext[UserContext]) -> WebSearchTool | None:
+    if not ctx.deps.location:
+        return None
+
+    return WebSearchTool(
+        search_context_size='medium',
+        user_location=WebSearchUserLocation(city=ctx.deps.location),
+    )
+
+
+async def test_dynamic_builtin_tool_configured():
+    model = TestModel()
+    agent = Agent(model, builtin_tools=[prepared_web_search], deps_type=UserContext)
+
+    user_context = UserContext(location='London')
+
+    with pytest.raises(UserError, match='TestModel does not support built-in tools'):
+        await agent.run('Hello', deps=user_context)
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 1
+    tool = tools[0]
+    assert isinstance(tool, WebSearchTool)
+    assert tool.user_location is not None
+    assert tool.user_location.get('city') == 'London'
+    assert tool.search_context_size == 'medium'
+
+
+async def test_dynamic_builtin_tool_omitted():
+    model = TestModel()
+    agent = Agent(model, builtin_tools=[prepared_web_search], deps_type=UserContext)
+
+    user_context = UserContext(location=None)
+
+    await agent.run('Hello', deps=user_context)
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 0
+
+
+async def test_mixed_static_and_dynamic_builtin_tools():
+    model = TestModel()
+
+    static_tool = CodeExecutionTool()
+    agent = Agent(model, builtin_tools=[static_tool, prepared_web_search], deps_type=UserContext)
+
+    # Case 1: Dynamic tool returns None
+    with pytest.raises(UserError, match='TestModel does not support built-in tools'):
+        await agent.run('Hello', deps=UserContext(location=None))
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 1
+    assert tools[0] == static_tool
+
+    # Case 2: Dynamic tool returns a tool
+    with pytest.raises(UserError, match='TestModel does not support built-in tools'):
+        await agent.run('Hello', deps=UserContext(location='Paris'))
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 2
+    assert tools[0] == static_tool
+    dynamic_tool = tools[1]
+    assert isinstance(dynamic_tool, WebSearchTool)
+    assert dynamic_tool.user_location is not None
+    assert dynamic_tool.user_location.get('city') == 'Paris'
+
+
+def sync_dynamic_tool(ctx: RunContext[UserContext]) -> WebSearchTool:
+    """Verify that synchronous functions work."""
+    return WebSearchTool(search_context_size='low')
+
+
+async def test_sync_dynamic_tool():
+    model = TestModel()
+    agent = Agent(model, builtin_tools=[sync_dynamic_tool], deps_type=UserContext)
+
+    with pytest.raises(UserError, match='TestModel does not support built-in tools'):
+        await agent.run('Hello', deps=UserContext(location='London'))
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 1
+    assert isinstance(tools[0], WebSearchTool)
+    assert tools[0].search_context_size == 'low'
+
+
+async def test_dynamic_tool_in_run_call():
+    """Verify dynamic tools can be passed to agent.run()."""
+    model = TestModel()
+    agent = Agent(model, deps_type=UserContext)
+
+    with pytest.raises(UserError, match='TestModel does not support built-in tools'):
+        await agent.run('Hello', deps=UserContext(location='Berlin'), builtin_tools=[prepared_web_search])
+
+    assert model.last_model_request_parameters is not None
+    tools = model.last_model_request_parameters.builtin_tools
+    assert len(tools) == 1
+    tool = tools[0]
+    assert isinstance(tool, WebSearchTool)
+    assert tool.user_location is not None
+    assert tool.user_location.get('city') == 'Berlin'
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 3490f0dd3e..f5cf196b7c 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -328,6 +328,7 @@ async def call_tool(
     'Give me a sentence with the biggest news in AI this week.': 'Scientists have developed a universal AI detector that can identify deepfake videos.',
     'How many days between 2000-01-01 and 2025-03-18?': 'There are 9,208 days between January 1, 2000, and March 18, 2025.',
     'What is 7 plus 5?': 'The answer is 12.',
+    'What is the weather like?': "It's currently raining in London.",
     'What is the weather like in West London and in Wiltshire?': (
         'The weather in West London is raining, while in Wiltshire it is sunny.'
     ),