Summary

GitLab MCP had been working correctly until yesterday.
Now, even though the GitLab MCP server starts and shows tools, no MCP tools appear in any client (Cursor, AMP, Windsurf).

All clients fail when parsing the tool list because inputSchema is returned as an empty object {}, which violates the MCP schema specification.

Current Behavior

• GitLab MCP server starts normally
• logs show tools, for example:

{
  "result": {
    "tools": [
      {
        "name": "merge_merge_request",
        "description": "Merge a merge request in a GitLab project",
        "inputSchema": {}
      },
      {
        "name": "execute_graphql",
        "description": "Execute a GitLab GraphQL query",
        "inputSchema": {}
      }
    ]
  }
}

Note: inputSchema is empty.

Client Log Errors

Error listing tools: [
  {
    "code": "invalid_literal",
    "expected": "object",
    "path": ["tools", 0, "inputSchema", "type"],
    "message": "Invalid literal value, expected \"object\""
  }
]

This indicates that inputSchema.type is missing, making the schema invalid.

Expected Behavior

All MCP clients should successfully load tools from the GitLab MCP server.

Per MCP specification, inputSchema must always include:

"inputSchema": {
  "type": "object",
  "properties": {}
}

Steps to Reproduce

Start GitLab MCP server

Open any MCP client (Cursor, Windsurf, AMP)

Tools fail to load

Inspect logs → schema validation error

Inspect logs → inputSchema: {} returned by server

Issue confirmed by multiple clients → Cursor, AMP, WindSurf .