"""Test output schema validation for lowlevel server.""" import json from collections.abc import Awaitable, Callable from typing import Any import anyio import pytest from mcp.client.session import ClientSession from mcp.server import Server from mcp.server.lowlevel import NotificationOptions from mcp.server.models import InitializationOptions from mcp.server.session import ServerSession from mcp.shared.message import SessionMessage from mcp.shared.session import RequestResponder from mcp.types import CallToolResult, ClientResult, ServerNotification, ServerRequest, TextContent, Tool async def run_tool_test( tools: list[Tool], call_tool_handler: Callable[[str, dict[str, Any]], Awaitable[Any]], test_callback: Callable[[ClientSession], Awaitable[CallToolResult]], ) -> CallToolResult | None: """Helper to run a tool test with minimal boilerplate. Args: tools: List of tools to register call_tool_handler: Handler function for tool calls test_callback: Async function that performs the test using the client session Returns: The result of the tool call """ server = Server("test") result = None @server.list_tools() async def list_tools(): return tools @server.call_tool() async def call_tool(name: str, arguments: dict[str, Any]): return await call_tool_handler(name, arguments) server_to_client_send, server_to_client_receive = anyio.create_memory_object_stream[SessionMessage](10) client_to_server_send, client_to_server_receive = anyio.create_memory_object_stream[SessionMessage](10) # Message handler for client async def message_handler( # pragma: no cover message: RequestResponder[ServerRequest, ClientResult] | ServerNotification | Exception, ) -> None: if isinstance(message, Exception): raise message # Server task async def run_server(): async with ServerSession( client_to_server_receive, server_to_client_send, InitializationOptions( server_name="test-server", server_version="1.0.0", capabilities=server.get_capabilities( notification_options=NotificationOptions(), experimental_capabilities={}, ), ), ) as server_session: async with anyio.create_task_group() as tg: async def handle_messages(): async for message in server_session.incoming_messages: await server._handle_message(message, server_session, {}, False) tg.start_soon(handle_messages) await anyio.sleep_forever() # Run the test async with anyio.create_task_group() as tg: tg.start_soon(run_server) async with ClientSession( server_to_client_receive, client_to_server_send, message_handler=message_handler, ) as client_session: # Initialize the session await client_session.initialize() # Run the test callback result = await test_callback(client_session) # Cancel the server task tg.cancel_scope.cancel() return result @pytest.mark.anyio async def test_content_only_without_output_schema(): """Test returning content only when no outputSchema is defined.""" tools = [ Tool( name="echo", description="Echo a message", inputSchema={ "type": "object", "properties": { "message": {"type": "string"}, }, "required": ["message"], }, # No outputSchema defined ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> list[TextContent]: if name == "echo": return [TextContent(type="text", text=f"Echo: {arguments['message']}")] else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("echo", {"message": "Hello"}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert isinstance(result.content[0], TextContent) assert result.content[0].text == "Echo: Hello" assert result.structuredContent is None @pytest.mark.anyio async def test_dict_only_without_output_schema(): """Test returning dict only when no outputSchema is defined.""" tools = [ Tool( name="get_info", description="Get structured information", inputSchema={ "type": "object", "properties": {}, }, # No outputSchema defined ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> dict[str, Any]: if name == "get_info": return {"status": "ok", "data": {"value": 42}} else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("get_info", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert isinstance(result.content[0], TextContent) # Check that the content is the JSON serialization assert json.loads(result.content[0].text) == {"status": "ok", "data": {"value": 42}} assert result.structuredContent == {"status": "ok", "data": {"value": 42}} @pytest.mark.anyio async def test_both_content_and_dict_without_output_schema(): """Test returning both content and dict when no outputSchema is defined.""" tools = [ Tool( name="process", description="Process data", inputSchema={ "type": "object", "properties": {}, }, # No outputSchema defined ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> tuple[list[TextContent], dict[str, Any]]: if name == "process": content = [TextContent(type="text", text="Processing complete")] data = {"result": "success", "count": 10} return (content, data) else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("process", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert isinstance(result.content[0], TextContent) assert result.content[0].text == "Processing complete" assert result.structuredContent == {"result": "success", "count": 10} @pytest.mark.anyio async def test_content_only_with_output_schema_error(): """Test error when outputSchema is defined but only content is returned.""" tools = [ Tool( name="structured_tool", description="Tool expecting structured output", inputSchema={ "type": "object", "properties": {}, }, outputSchema={ "type": "object", "properties": { "result": {"type": "string"}, }, "required": ["result"], }, ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> list[TextContent]: # This returns only content, but outputSchema expects structured data return [TextContent(type="text", text="This is not structured")] async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("structured_tool", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify error assert result is not None assert result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert isinstance(result.content[0], TextContent) assert "Output validation error: outputSchema defined but no structured output returned" in result.content[0].text @pytest.mark.anyio async def test_valid_dict_with_output_schema(): """Test valid dict output matching outputSchema.""" tools = [ Tool( name="calc", description="Calculate result", inputSchema={ "type": "object", "properties": { "x": {"type": "number"}, "y": {"type": "number"}, }, "required": ["x", "y"], }, outputSchema={ "type": "object", "properties": { "sum": {"type": "number"}, "product": {"type": "number"}, }, "required": ["sum", "product"], }, ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> dict[str, Any]: if name == "calc": x = arguments["x"] y = arguments["y"] return {"sum": x + y, "product": x * y} else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("calc", {"x": 3, "y": 4}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" # Check JSON serialization assert json.loads(result.content[0].text) == {"sum": 7, "product": 12} assert result.structuredContent == {"sum": 7, "product": 12} @pytest.mark.anyio async def test_invalid_dict_with_output_schema(): """Test dict output that doesn't match outputSchema.""" tools = [ Tool( name="user_info", description="Get user information", inputSchema={ "type": "object", "properties": {}, }, outputSchema={ "type": "object", "properties": { "name": {"type": "string"}, "age": {"type": "integer"}, }, "required": ["name", "age"], }, ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> dict[str, Any]: if name == "user_info": # Missing required 'age' field return {"name": "Alice"} else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("user_info", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify error assert result is not None assert result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert isinstance(result.content[0], TextContent) assert "Output validation error:" in result.content[0].text assert "'age' is a required property" in result.content[0].text @pytest.mark.anyio async def test_both_content_and_valid_dict_with_output_schema(): """Test returning both content and valid dict with outputSchema.""" tools = [ Tool( name="analyze", description="Analyze data", inputSchema={ "type": "object", "properties": { "text": {"type": "string"}, }, "required": ["text"], }, outputSchema={ "type": "object", "properties": { "sentiment": {"type": "string", "enum": ["positive", "negative", "neutral"]}, "confidence": {"type": "number", "minimum": 0, "maximum": 1}, }, "required": ["sentiment", "confidence"], }, ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> tuple[list[TextContent], dict[str, Any]]: if name == "analyze": content = [TextContent(type="text", text=f"Analysis of: {arguments['text']}")] data = {"sentiment": "positive", "confidence": 0.95} return (content, data) else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("analyze", {"text": "Great job!"}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert result.content[0].text == "Analysis of: Great job!" assert result.structuredContent == {"sentiment": "positive", "confidence": 0.95} @pytest.mark.anyio async def test_tool_call_result(): """Test returning ToolCallResult when no outputSchema is defined.""" tools = [ Tool( name="get_info", description="Get structured information", inputSchema={ "type": "object", "properties": {}, }, # No outputSchema for direct return of tool call result ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> CallToolResult: if name == "get_info": return CallToolResult( content=[TextContent(type="text", text="Results calculated")], structuredContent={"status": "ok", "data": {"value": 42}}, _meta={"some": "metadata"}, ) else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("get_info", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify results assert result is not None assert not result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert result.content[0].text == "Results calculated" assert isinstance(result.content[0], TextContent) assert result.structuredContent == {"status": "ok", "data": {"value": 42}} assert result.meta == {"some": "metadata"} @pytest.mark.anyio async def test_output_schema_type_validation(): """Test outputSchema validates types correctly.""" tools = [ Tool( name="stats", description="Get statistics", inputSchema={ "type": "object", "properties": {}, }, outputSchema={ "type": "object", "properties": { "count": {"type": "integer"}, "average": {"type": "number"}, "items": {"type": "array", "items": {"type": "string"}}, }, "required": ["count", "average", "items"], }, ) ] async def call_tool_handler(name: str, arguments: dict[str, Any]) -> dict[str, Any]: if name == "stats": # Wrong type for 'count' - should be integer return {"count": "five", "average": 2.5, "items": ["a", "b"]} else: # pragma: no cover raise ValueError(f"Unknown tool: {name}") async def test_callback(client_session: ClientSession) -> CallToolResult: return await client_session.call_tool("stats", {}) result = await run_tool_test(tools, call_tool_handler, test_callback) # Verify error assert result is not None assert result.isError assert len(result.content) == 1 assert result.content[0].type == "text" assert "Output validation error:" in result.content[0].text assert "'five' is not of type 'integer'" in result.content[0].text