fix: Update context logging type hints to match MCP spec

Author: rakib-liberatelabs

Diff for: src/mcp/server/fastmcp/server.py

@@ -660,7 +660,7 @@ async def read_resource(self, uri: str | AnyUrl) -> Iterable[ReadResourceContent
     async def log(
         self,
         level: Literal["debug", "info", "warning", "error"],
-        message: str,
+        message: Any,
         *,
         logger_name: str | None = None,
     ) -> None:
@@ -696,18 +696,38 @@ def session(self):
         return self.request_context.session
 
     # Convenience methods for common log levels
-    async def debug(self, message: str, **extra: Any) -> None:
-        """Send a debug log message."""
+    async def debug(self, message: Any, **extra: Any) -> None:
+        """Send a debug log message.
+        
+        Args:
+            message: The message to log. Can be any JSON-serializable type.
+            **extra: Additional structured data to include
+        """
         await self.log("debug", message, **extra)
 
-    async def info(self, message: str, **extra: Any) -> None:
-        """Send an info log message."""
+    async def info(self, message: Any, **extra: Any) -> None:
+        """Send an info log message.
+        
+        Args:
+            message: The message to log. Can be any JSON-serializable type.
+            **extra: Additional structured data to include
+        """
         await self.log("info", message, **extra)
 
-    async def warning(self, message: str, **extra: Any) -> None:
-        """Send a warning log message."""
+    async def warning(self, message: Any, **extra: Any) -> None:
+        """Send a warning log message.
+        
+        Args:
+            message: The message to log. Can be any JSON-serializable type.
+            **extra: Additional structured data to include
+        """
         await self.log("warning", message, **extra)
 
-    async def error(self, message: str, **extra: Any) -> None:
-        """Send an error log message."""
+    async def error(self, message: Any, **extra: Any) -> None:
+        """Send an error log message.
+        
+        Args:
+            message: The message to log. Can be any JSON-serializable type.
+            **extra: Additional structured data to include
+        """
         await self.log("error", message, **extra)

Diff for: tests/server/fastmcp/test_server.py

@@ -554,6 +554,43 @@ async def logging_tool(msg: str, ctx: Context) -> str:
                     level="error", data="Error message", logger=None
                 )
 
+    @pytest.mark.anyio
+    async def test_context_logging_any_type(self):
+        """Test that context logging methods can handle different types of messages."""
+        from unittest.mock import patch
+
+        import mcp.server.session
+
+        mcp = FastMCP()
+
+        async def logging_tool(ctx: Context) -> str:
+            # Test with different data types
+            await ctx.debug(42)  # integer
+            await ctx.info(["list", "of", "items"])  # list
+            await ctx.warning({"key": "value"})  # dictionary
+            await ctx.error(3.14)  # float
+            return "Logged messages of different types"
+
+        mcp.add_tool(logging_tool)
+
+        with patch("mcp.server.session.ServerSession.send_log_message") as mock_log:
+            async with client_session(mcp._mcp_server) as client:
+                result = await client.call_tool("logging_tool", {})
+                assert len(result.content) == 1
+                content = result.content[0]
+                assert isinstance(content, TextContent)
+                assert "Logged messages of different types" in content.text
+
+                assert mock_log.call_count == 4
+                mock_log.assert_any_call(level="debug", data=42, logger=None)
+                mock_log.assert_any_call(
+                    level="info", data=["list", "of", "items"], logger=None
+                )
+                mock_log.assert_any_call(
+                    level="warning", data={"key": "value"}, logger=None
+                )
+                mock_log.assert_any_call(level="error", data=3.14, logger=None)
+
     @pytest.mark.anyio
     async def test_optional_context(self):
         """Test that context is optional."""