Getting Invalid Arguments when using introspect-schema in Winsurf

[floww-dev156]

This is the Error I'm getting.

MCP error -32602: Invalid arguments for tool introspect-schema: [ { "code": "invalid_type", "expected": "object", "received": "undefined", "path": [], "message": "Required" } ] (Code -32602)

my mcp config is in this fashion

{ "mcpServers": { "mcp-graphql": { "command": "npx", "args": ["mcp-graphql"], "env": { "ENDPOINT": "http://localhost:3000/graphql" } } } }

[suresh-prakash]

+1. This is happening even after providing a path to the local schema file.

[LarsDepuydt]

I had the same issue using a tool called mcphost, which runs Ollama models with MCP support.

The core issue is that the MCP server expects {}, while undefined is sent by the MCP client.

A fix on the server side is to change the following line in the source code to this

{
  argument: z.string(),
},

This will add an extra (unused) argument to the tool, forcing the MCP client to send a JSON struct, instead of undefined.
(Remember to build a new code version, using npm run build)

Note: this is not a 'solution', but merely a temporary workaround

[blurrah]

@floww-dev156 @suresh-prakash @LarsDepuydt Sorry for the delay, I've added an optional argument to the introspection tool call in v2.0.2

I am looking into moving back to the original MCP server syntax which doesn't force me to set up a zod shape for tool call inputs, should fix this without the workaround.

[LarsDepuydt]

@blurrah For me, the workaround only works with a non-optional argument, which forces my MCP client to provide an object instead of undefined, leading to the error

[blurrah]

I think this might have been fixed in the SDK. I'll check if that fixes it later today otherwise I'll remove the optional

[blurrah]

Can you retry with 2.0.3 please @LarsDepuydt? Couldn't properly reproduce yet so quick SDK update to see if that works

[LarsDepuydt]

@blurrah Version 2.0.3 leads to the same error as before

Error calling tool introspect-schema: MCP error -32602: Invalid arguments for tool introspect-schema: [
  {                                                                                                    
    "code": "invalid_type",                                                                            
    "expected": "object",                                                                              
    "received": "undefined",                                                                           
    "path": [],                                                                                        
    "message": "Required"                                                                              
  }                                                                                                    
] 

I have the code cloned locally, and the only thing that worked for me (until now) was the forcing of a dummy argument (which is not optional, as that leads to undefined being sent again). But this might be an issue with the MCP host I'm using