diff --git a/openhands-agent-server/openhands/agent_server/conversation_service.py b/openhands-agent-server/openhands/agent_server/conversation_service.py
index 611f0dbc51..9d5fbba60e 100644
--- a/openhands-agent-server/openhands/agent_server/conversation_service.py
+++ b/openhands-agent-server/openhands/agent_server/conversation_service.py
@@ -189,6 +189,32 @@ async def start_conversation(
             )
             return conversation_info, False
 
+        # Dynamically register tools from client's registry
+        if request.tool_module_qualnames:
+            import importlib
+
+            for tool_name, module_qualname in request.tool_module_qualnames.items():
+                try:
+                    # Import the module to trigger tool auto-registration
+                    importlib.import_module(module_qualname)
+                    logger.debug(
+                        f"Tool '{tool_name}' registered via module '{module_qualname}'"
+                    )
+                except ImportError as e:
+                    logger.warning(
+                        f"Failed to import module '{module_qualname}' for tool "
+                        f"'{tool_name}': {e}. Tool will not be available."
+                    )
+                    # Continue even if some tools fail to register
+                    # The agent will fail gracefully if it tries to use unregistered
+                    # tools
+            if request.tool_module_qualnames:
+                logger.info(
+                    f"Dynamically registered {len(request.tool_module_qualnames)} "
+                    f"tools for conversation {conversation_id}: "
+                    f"{list(request.tool_module_qualnames.keys())}"
+                )
+
         stored = StoredConversation(id=conversation_id, **request.model_dump())
         event_service = await self._start_event_service(stored)
         initial_message = request.initial_message
diff --git a/openhands-agent-server/openhands/agent_server/models.py b/openhands-agent-server/openhands/agent_server/models.py
index a19080f5e9..6258c95dc5 100644
--- a/openhands-agent-server/openhands/agent_server/models.py
+++ b/openhands-agent-server/openhands/agent_server/models.py
@@ -97,6 +97,14 @@ class StartConversationRequest(BaseModel):
         default_factory=dict,
         description="Secrets available in the conversation",
     )
+    tool_module_qualnames: dict[str, str] = Field(
+        default_factory=dict,
+        description=(
+            "Mapping of tool names to their module qualnames from the client's "
+            "registry. These modules will be dynamically imported on the server "
+            "to register the tools for this conversation."
+        ),
+    )
 
 
 class StoredConversation(StartConversationRequest):
diff --git a/openhands-agent-server/openhands/agent_server/tool_router.py b/openhands-agent-server/openhands/agent_server/tool_router.py
index b37a32e9e8..2583afd296 100644
--- a/openhands-agent-server/openhands/agent_server/tool_router.py
+++ b/openhands-agent-server/openhands/agent_server/tool_router.py
@@ -4,12 +4,13 @@
 
 from openhands.sdk.tool.registry import list_registered_tools
 from openhands.tools.preset.default import register_default_tools
-from openhands.tools.preset.planning import register_planning_tools
 
 
 tool_router = APIRouter(prefix="/tools", tags=["Tools"])
+# Register default tools for backward compatibility
+# Planning tools and other custom tools are now dynamically registered
+# when creating a RemoteConversation
 register_default_tools(enable_browser=True)
-register_planning_tools()
 
 
 # Tool listing
diff --git a/openhands-sdk/openhands/sdk/conversation/impl/remote_conversation.py b/openhands-sdk/openhands/sdk/conversation/impl/remote_conversation.py
index 9b53ee3ea7..fbd15d81ca 100644
--- a/openhands-sdk/openhands/sdk/conversation/impl/remote_conversation.py
+++ b/openhands-sdk/openhands/sdk/conversation/impl/remote_conversation.py
@@ -451,6 +451,9 @@ def __init__(
         self._client = workspace.client
 
         if conversation_id is None:
+            # Import here to avoid circular imports
+            from openhands.sdk.tool.registry import get_tool_module_qualnames
+
             payload = {
                 "agent": agent.model_dump(
                     mode="json", context={"expose_secrets": True}
@@ -462,6 +465,8 @@ def __init__(
                 "workspace": LocalWorkspace(
                     working_dir=self.workspace.working_dir
                 ).model_dump(),
+                # Include tool module qualnames for dynamic registration on server
+                "tool_module_qualnames": get_tool_module_qualnames(),
             }
             resp = _send_request(
                 self._client, "POST", "/api/conversations", json=payload
diff --git a/openhands-sdk/openhands/sdk/tool/registry.py b/openhands-sdk/openhands/sdk/tool/registry.py
index 0095b2b770..2d1942c66e 100644
--- a/openhands-sdk/openhands/sdk/tool/registry.py
+++ b/openhands-sdk/openhands/sdk/tool/registry.py
@@ -29,6 +29,7 @@
 
 _LOCK = RLock()
 _REG: dict[str, Resolver] = {}
+_MODULE_QUALNAMES: dict[str, str] = {}  # Maps tool name to module qualname
 
 
 def _resolver_from_instance(name: str, tool: ToolDefinition) -> Resolver:
@@ -137,11 +138,22 @@ def register_tool(
             "(3) a callable factory returning a Sequence[ToolDefinition]"
         )
 
+    # Track the module qualname for this tool
+    module_qualname = None
+    if isinstance(factory, type):
+        module_qualname = factory.__module__
+    elif callable(factory):
+        module_qualname = getattr(factory, "__module__", None)
+    elif isinstance(factory, ToolDefinition):
+        module_qualname = factory.__class__.__module__
+
     with _LOCK:
         # TODO: throw exception when registering duplicate name tools
         if name in _REG:
             logger.warning(f"Duplicate tool name registerd {name}")
         _REG[name] = resolver
+        if module_qualname:
+            _MODULE_QUALNAMES[name] = module_qualname
 
 
 def resolve_tool(
@@ -159,3 +171,14 @@ def resolve_tool(
 def list_registered_tools() -> list[str]:
     with _LOCK:
         return list(_REG.keys())
+
+
+def get_tool_module_qualnames() -> dict[str, str]:
+    """Get a mapping of tool names to their module qualnames.
+
+    Returns:
+        A dictionary mapping tool names to module qualnames (e.g.,
+        {"glob": "openhands.tools.glob.definition"}).
+    """
+    with _LOCK:
+        return dict(_MODULE_QUALNAMES)
diff --git a/tests/agent_server/test_conversation_router.py b/tests/agent_server/test_conversation_router.py
index dc3106083c..9d332e35c2 100644
--- a/tests/agent_server/test_conversation_router.py
+++ b/tests/agent_server/test_conversation_router.py
@@ -1169,3 +1169,109 @@ def test_generate_conversation_title_invalid_params(
         assert response.status_code == 422  # Validation error
     finally:
         client.app.dependency_overrides.clear()
+
+
+def test_start_conversation_with_tool_module_qualnames(
+    client, mock_conversation_service, sample_conversation_info
+):
+    """Test start_conversation endpoint with tool_module_qualnames field."""
+
+    # Mock the service response
+    mock_conversation_service.start_conversation.return_value = (
+        sample_conversation_info,
+        True,
+    )
+
+    # Override the dependency
+    client.app.dependency_overrides[get_conversation_service] = (
+        lambda: mock_conversation_service
+    )
+
+    try:
+        request_data = {
+            "agent": {
+                "llm": {
+                    "model": "gpt-4o",
+                    "api_key": "test-key",
+                    "usage_id": "test-llm",
+                },
+                "tools": [
+                    {"name": "glob"},
+                    {"name": "grep"},
+                    {"name": "planning_file_editor"},
+                ],
+            },
+            "workspace": {"working_dir": "/tmp/test"},
+            "tool_module_qualnames": {
+                "glob": "openhands.tools.glob.definition",
+                "grep": "openhands.tools.grep.definition",
+                "planning_file_editor": (
+                    "openhands.tools.planning_file_editor.definition"
+                ),
+            },
+        }
+
+        response = client.post("/api/conversations", json=request_data)
+
+        assert response.status_code == 201
+        data = response.json()
+        assert data["id"] == str(sample_conversation_info.id)
+
+        # Verify service was called
+        mock_conversation_service.start_conversation.assert_called_once()
+        call_args = mock_conversation_service.start_conversation.call_args
+        request_arg = call_args[0][0]
+        assert hasattr(request_arg, "tool_module_qualnames")
+        assert request_arg.tool_module_qualnames == {
+            "glob": "openhands.tools.glob.definition",
+            "grep": "openhands.tools.grep.definition",
+            "planning_file_editor": ("openhands.tools.planning_file_editor.definition"),
+        }
+    finally:
+        client.app.dependency_overrides.clear()
+
+
+def test_start_conversation_without_tool_module_qualnames(
+    client, mock_conversation_service, sample_conversation_info
+):
+    """Test start_conversation endpoint without tool_module_qualnames field."""
+
+    # Mock the service response
+    mock_conversation_service.start_conversation.return_value = (
+        sample_conversation_info,
+        True,
+    )
+
+    # Override the dependency
+    client.app.dependency_overrides[get_conversation_service] = (
+        lambda: mock_conversation_service
+    )
+
+    try:
+        request_data = {
+            "agent": {
+                "llm": {
+                    "model": "gpt-4o",
+                    "api_key": "test-key",
+                    "usage_id": "test-llm",
+                },
+                "tools": [{"name": "TerminalTool"}],
+            },
+            "workspace": {"working_dir": "/tmp/test"},
+        }
+
+        response = client.post("/api/conversations", json=request_data)
+
+        assert response.status_code == 201
+        data = response.json()
+        assert data["id"] == str(sample_conversation_info.id)
+
+        # Verify service was called
+        mock_conversation_service.start_conversation.assert_called_once()
+        call_args = mock_conversation_service.start_conversation.call_args
+        request_arg = call_args[0][0]
+        assert hasattr(request_arg, "tool_module_qualnames")
+        # Should default to empty dict
+        assert request_arg.tool_module_qualnames == {}
+    finally:
+        client.app.dependency_overrides.clear()
diff --git a/tests/sdk/test_registry_qualnames.py b/tests/sdk/test_registry_qualnames.py
new file mode 100644
index 0000000000..2d691c3ec6
--- /dev/null
+++ b/tests/sdk/test_registry_qualnames.py
@@ -0,0 +1,68 @@
+"""Tests for tool registry module qualname tracking."""
+
+from openhands.sdk.tool.registry import (
+    get_tool_module_qualnames,
+    list_registered_tools,
+    register_tool,
+)
+
+
+def test_get_tool_module_qualnames_with_class():
+    """Test that module qualnames are tracked when registering a class."""
+    from openhands.tools.glob import GlobTool
+
+    # Register the GlobTool class
+    register_tool("test_glob_class", GlobTool)
+
+    # Get the module qualnames
+    qualnames = get_tool_module_qualnames()
+
+    # Verify the tool is tracked with its module
+    assert "test_glob_class" in qualnames
+    assert qualnames["test_glob_class"] == "openhands.tools.glob.definition"
+
+
+def test_get_tool_module_qualnames_with_callable():
+    """Test that module qualnames are tracked when registering a callable."""
+
+    def test_factory(conv_state):
+        return []
+
+    # Register the callable
+    register_tool("test_callable", test_factory)
+
+    # Get the module qualnames
+    qualnames = get_tool_module_qualnames()
+
+    # Verify the tool is tracked with its module
+    assert "test_callable" in qualnames
+    assert "test_registry_qualnames" in qualnames["test_callable"]
+
+
+def test_get_tool_module_qualnames_after_import():
+    """Test that importing a tool module registers it with qualname."""
+    # Import glob tool module to trigger auto-registration
+    import openhands.tools.glob.definition  # noqa: F401
+
+    # Get registered tools
+    registered_tools = list_registered_tools()
+
+    # Should have glob registered
+    assert "glob" in registered_tools
+
+    # Get module qualnames
+    qualnames = get_tool_module_qualnames()
+
+    # Verify glob has its module qualname tracked
+    if "glob" in qualnames:
+        assert qualnames["glob"] == "openhands.tools.glob.definition"
+
+
+def test_get_tool_module_qualnames_returns_copy():
+    """Test that get_tool_module_qualnames returns a copy, not the original dict."""
+    qualnames1 = get_tool_module_qualnames()
+    qualnames2 = get_tool_module_qualnames()
+
+    # Should be equal but not the same object
+    assert qualnames1 == qualnames2
+    assert qualnames1 is not qualnames2