Fix exclude_args with non-serializable types

Fixes issue #2431 where exclude_args fails when excluded parameters have
non-serializable types (e.g., ServerSession). The fix excludes parameters
from function annotations before Pydantic tries to serialize them.

Also adds deprecation notice that exclude_args will be deprecated in
FastMCP 2.14 in favor of dependency injection.

tests/server/test_tool_exclude_args.py

@@ -1,6 +1,7 @@
 from typing import Any
 
 import pytest
+from mcp.server.session import ServerSession
 
 from fastmcp import Client, FastMCP
 from fastmcp.tools.tool import Tool
@@ -92,3 +93,32 @@ async def test_tool_functionality_with_exclude_args():
             "create_item", {"name": "test_item", "value": 42}
         )
         assert result.data == {"name": "test_item", "value": 42}
+
+
+async def test_exclude_args_with_non_serializable_type():
+    """Test that exclude_args works even when the excluded parameter type can't be serialized.
+
+    This test ensures that exclude_args works correctly when the excluded parameter
+    has a type that Pydantic cannot serialize (like ServerSession). The bug was that
+    get_cached_typeadapter would try to serialize all parameters before compress_schema
+    could exclude them, causing a PydanticSchemaGenerationError.
+    """
+
+    def my_tool(message: str, session: ServerSession | None = None) -> str:
+        """A tool that takes a non-serializable Session parameter."""
+        return message
+
+    # This should not raise an error even though ServerSession can't be serialized
+    tool = Tool.from_function(
+        my_tool,
+        name="my_tool",
+        exclude_args=["session"],
+    )
+
+    # Verify the tool was created successfully
+    assert tool is not None
+    assert tool.name == "my_tool"
+
+    # Verify the session parameter is excluded from the schema
+    assert "session" not in tool.parameters["properties"]
+    assert "message" in tool.parameters["properties"]