diff --git a/tests/test_tool_manager.py b/tests/test_tool_manager.py
new file mode 100644
index 000000000..16f244231
--- /dev/null
+++ b/tests/test_tool_manager.py
@@ -0,0 +1,119 @@
+"""Test tool registration and execution."""
+
+import pytest
+from pydantic import BaseModel
+
+from fastmcp.exceptions import ToolError
+from fastmcp.tools import ToolManager
+
+
+class TestAddTools:
+    def test_basic_function(self):
+        """Test registering and running a basic function."""
+
+        def add(a: int, b: int) -> int:
+            """Add two numbers."""
+            return a + b
+
+        manager = ToolManager()
+        manager.add_tool(add)
+
+        tool = manager.get_tool("add")
+        assert tool is not None
+        assert tool.name == "add"
+        assert tool.description == "Add two numbers."
+        assert tool.is_async is False
+        assert tool.parameters["properties"]["a"]["type"] == "integer"
+        assert tool.parameters["properties"]["b"]["type"] == "integer"
+
+    async def test_async_function(self):
+        """Test registering and running an async function."""
+
+        async def fetch_data(url: str) -> str:
+            """Fetch data from URL."""
+            return f"Data from {url}"
+
+        manager = ToolManager()
+        manager.add_tool(fetch_data)
+
+        tool = manager.get_tool("fetch_data")
+        assert tool is not None
+        assert tool.name == "fetch_data"
+        assert tool.description == "Fetch data from URL."
+        assert tool.is_async is True
+        assert tool.parameters["properties"]["url"]["type"] == "string"
+
+    def test_pydantic_model_function(self):
+        """Test registering a function that takes a Pydantic model."""
+
+        class UserInput(BaseModel):
+            name: str
+            age: int
+
+        def create_user(user: UserInput, flag: bool) -> dict:
+            """Create a new user."""
+            return {"id": 1, **user.model_dump()}
+
+        manager = ToolManager()
+        manager.add_tool(create_user)
+
+        tool = manager.get_tool("create_user")
+        assert tool is not None
+        assert tool.name == "create_user"
+        assert tool.description == "Create a new user."
+        assert tool.is_async is False
+        assert "name" in tool.parameters["$defs"]["UserInput"]["properties"]
+        assert "age" in tool.parameters["$defs"]["UserInput"]["properties"]
+        assert "flag" in tool.parameters["properties"]
+
+    def test_add_invalid_tool(self):
+        manager = ToolManager()
+        with pytest.raises(AttributeError):
+            manager.add_tool(1)
+
+
+class TestCallTools:
+    async def test_call_tool(self):
+        def add(a: int, b: int) -> int:
+            """Add two numbers."""
+            return a + b
+
+        manager = ToolManager()
+        manager.add_tool(add)
+        result = await manager.call_tool("add", {"a": 1, "b": 2})
+        assert result == 3
+
+    async def test_call_async_tool(self):
+        async def double(n: int) -> int:
+            """Double a number."""
+            return n * 2
+
+        manager = ToolManager()
+        manager.add_tool(double)
+        result = await manager.call_tool("double", {"n": 5})
+        assert result == 10
+
+    async def test_call_tool_with_default_args(self):
+        def add(a: int, b: int = 1) -> int:
+            """Add two numbers."""
+            return a + b
+
+        manager = ToolManager()
+        manager.add_tool(add)
+        result = await manager.call_tool("add", {"a": 1})
+        assert result == 2
+
+    async def test_call_tool_with_missing_args(self):
+        def add(a: int, b: int) -> int:
+            """Add two numbers."""
+            return a + b
+
+        manager = ToolManager()
+        manager.add_tool(add)
+        with pytest.raises(ToolError):
+            await manager.call_tool("add", {"a": 1})
+
+    async def test_call_unknown_tool(self):
+        manager = ToolManager()
+        with pytest.raises(ToolError):
+            await manager.call_tool("unknown", {"a": 1})