Why am I experiencing an internal error when using Pipedream MCP to call the cal-com-create-booking action?

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1

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Hi! I’m using Pipedream MCP to call the cal-com-create-booking action and I’m getting a confusing internal error. Here’s everything I have.

MCP Invocation Payload:

{
    "name": "John Doe",
    "email": "[john.doe@example.com](mailto:john.doe@example.com)",
    "startTime": "2025-07-01T13:00:00Z",
    "endTime": "2025-07-01T13:15:00Z",
    "language": "fr",
    "timeZone": "Europe/London",
    "eventTypeId": "123456"
}

MCP returned:

{
  "success": true,
  "mcp_result": true,
  "result": {
    "content": {
      "exports": {
        "debug": {
          "status": 500,
          "statusText": "Internal Server Error",
          "data": {
            "message": "An error occurred while querying the database.",
            "data": null
          }
        }
      }
    },
    "os": [
      {
        "ts": 1751301169986,
        "k": "error",
        "err": {
          "name": "TypeError",
          "message": "error.indexOf is not a function",
          "stack": "TypeError: error.indexOf is not a function\n  at Object.run (file:///tmp/__pdg__/dist/code/.../create-booking.mjs:86:54)\n  at process.processTicksAndRejections (node:internal/process/task_queues:95:5)\n  at async .../component_maker.mjs:166:11"
        }
      }
    ]
  }
}

Would love any help to debug or validate whether this is an MCP-level issue or if I should change something in my input. Thanks a lot :pray:

2

Seems potentially not related to MCP specifically, but maybe the underlying tool. Can you try it in the SDK playground here?

3

It does work using the SDK playground, but not with MCP. FYI we requested this integration a few weeks ago, if that makes any difference. Thanks !

4

How are you calling the MCP server?

5

We’re calling the MCP server via HTTP POST with JSON-RPC 2.0 format ({“jsonrpc”: “2.0”, “method”: “tools/call”, “params”: {“name”: “cal-com-create-booking”, “arguments”: {…}}}) using Bearer auth and standard MCP protocol - This has worked for us when using other integrations, even using other cal.com actions via pipedream mcp, just not this specific one.

6

What tool-mode are you using?

7

Tools-only mode

8

And are you reloading tools?

9

Not in this specific case as i think that there are no dynamic props that are required

10

Hello ! Do we have an update on this issue ? Thank you very much !

11

Seems like something is up with the tool — I can’t get it to work in the playground, will forward to the team to investigate. Tracking here: