diff --git a/src/oss/langchain/middleware/built-in.mdx b/src/oss/langchain/middleware/built-in.mdx
index f08acb05f7..95e3b865b0 100644
--- a/src/oss/langchain/middleware/built-in.mdx
+++ b/src/oss/langchain/middleware/built-in.mdx
@@ -1124,11 +1124,11 @@ const agent = createAgent({
 </ParamField>
 
 <ParamField body="max_tools" type="number">
-    Maximum number of tools to select. Defaults to no limit.
+    Maximum number of tools to select. If the model selects more, only the first max_tools will be used. No limit if not specified.
 </ParamField>
 
 <ParamField body="always_include" type="list[string]">
-    List of tool names to always include in the selection
+    Tool names to always include regardless of selection. These do not count against the max_tools limit.
 </ParamField>
 :::
 
@@ -1137,12 +1137,16 @@ const agent = createAgent({
     Model for tool selection. Can be a model identifier string (e.g., `'openai:gpt-4o-mini'`) or a `BaseChatModel` instance. Defaults to the agent's main model.
 </ParamField>
 
+<ParamField body="systemPrompt" type="string">
+    Instructions for the selection model. Uses built-in prompt if not specified.
+</ParamField>
+
 <ParamField body="maxTools" type="number">
-    Maximum number of tools to select. Defaults to no limit.
+    Maximum number of tools to select. If the model selects more, only the first maxTools will be used. No limit if not specified.
 </ParamField>
 
 <ParamField body="alwaysInclude" type="string[]">
-    Array of tool names to always include in the selection
+    Tool names to always include regardless of selection. These do not count against the maxTools limit.
 </ParamField>
 :::