From d4fc44feb423dc6e6b9d6ef24e4e8e87f960ea65 Mon Sep 17 00:00:00 2001
From: William Easton <bill.easton@elastic.co>
Date: Mon, 4 Aug 2025 08:41:05 -0500
Subject: [PATCH] Fix method-bound tools (#1360)

---
 src/fastmcp/utilities/types.py      |  7 ++++++-
 tests/utilities/test_typeadapter.py | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/fastmcp/utilities/types.py b/src/fastmcp/utilities/types.py
index 5b2d22fe1..246432ac6 100644
--- a/src/fastmcp/utilities/types.py
+++ b/src/fastmcp/utilities/types.py
@@ -101,7 +101,12 @@ def get_cached_typeadapter(cls: T) -> TypeAdapter[T]:
                 new_func.__module__ = cls.__module__
                 new_func.__qualname__ = getattr(cls, "__qualname__", cls.__name__)
                 new_func.__annotations__ = processed_hints
-                return TypeAdapter(new_func)
+
+                if inspect.ismethod(cls):
+                    new_method = types.MethodType(new_func, cls.__self__)
+                    return TypeAdapter(new_method)
+                else:
+                    return TypeAdapter(new_func)
 
     return TypeAdapter(cls)
 
diff --git a/tests/utilities/test_typeadapter.py b/tests/utilities/test_typeadapter.py
index a32d7fcb0..941cd1db9 100644
--- a/tests/utilities/test_typeadapter.py
+++ b/tests/utilities/test_typeadapter.py
@@ -37,6 +37,19 @@ class SomeComplexModel(BaseModel):
     y: dict[int, str]
 
 
+class ClassWithMethods:
+    def do_something(self, x: int) -> int:
+        return x
+
+    def do_something_annotated(
+        self, x: Annotated[int, Field(description="A description")]
+    ) -> int:
+        return x
+
+    def do_something_return_none(self) -> None:
+        return None
+
+
 def complex_arguments_fn(
     an_int: int,
     must_be_none: None,
@@ -242,3 +255,19 @@ def test_str_vs_int():
     type_adapter = get_cached_typeadapter(func_with_str_and_int)
     result = type_adapter.validate_python({"a": "123", "b": 123})
     assert result == "123"
+
+
+def test_class_with_methods():
+    """Test that class methods are not included in the schema"""
+    class_with_methods = ClassWithMethods()
+    type_adapter = get_cached_typeadapter(class_with_methods.do_something)
+    schema = type_adapter.json_schema()
+    assert "self" not in schema["properties"]
+
+    type_adapter = get_cached_typeadapter(class_with_methods.do_something_annotated)
+    schema = type_adapter.json_schema()
+    assert "self" not in schema["properties"]
+
+    type_adapter = get_cached_typeadapter(class_with_methods.do_something_return_none)
+    schema = type_adapter.json_schema()
+    assert "self" not in schema["properties"]