add examples to param transformation

src/fastmcp/tools/tool_transform.py

@@ -97,6 +97,7 @@ class ArgTransform:
         type: New type for the argument. Use ... for no change.
         hide: If True, hide this argument from clients but pass a constant value to parent.
         required: If True, make argument required (remove default). Use ... for no change.
+        examples: Examples for the argument. Use ... for no change.
 
     Examples:
         # Rename argument 'old_name' to 'new_name'
@@ -137,6 +138,7 @@ class ArgTransform:
     type: Any | EllipsisType = NotSet
     hide: bool = False
     required: Literal[True] | EllipsisType = NotSet
+    examples: Any | EllipsisType = NotSet
 
     def __post_init__(self):
         """Validate that only one of default or default_factory is provided."""
@@ -584,6 +586,10 @@ class TransformedTool(Tool):
             # Update the schema with the type information from TypeAdapter
             new_schema.update(type_schema)
 
+        # Handle examples transformation
+        if transform.examples is not NotSet:
+            new_schema["examples"] = transform.examples
+
         return new_name, new_schema, is_required
 
     @staticmethod

tests/tools/test_tool_transform.py

@@ -987,3 +987,35 @@ class TestEnableDisable:
 
             with pytest.raises(ToolError):
                 await client.call_tool("new_add", {"x": 1, "y": 2})
+
+
+def test_arg_transform_examples_in_schema(add_tool):
+    # Simple example
+    new_tool = Tool.from_tool(
+        add_tool,
+        transform_args={
+            "old_x": ArgTransform(examples=[1, 2, 3]),
+        },
+    )
+    prop = get_property(new_tool, "old_x")
+    assert prop["examples"] == [1, 2, 3]
+
+    # Nested example (e.g., for array type)
+    new_tool2 = Tool.from_tool(
+        add_tool,
+        transform_args={
+            "old_x": ArgTransform(examples=[["a", "b"], ["c", "d"]]),
+        },
+    )
+    prop2 = get_property(new_tool2, "old_x")
+    assert prop2["examples"] == [["a", "b"], ["c", "d"]]
+
+    # If not set, should not be present
+    new_tool3 = Tool.from_tool(
+        add_tool,
+        transform_args={
+            "old_x": ArgTransform(),
+        },
+    )
+    prop3 = get_property(new_tool3, "old_x")
+    assert "examples" not in prop3