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claude-code - 💡(How to fix) Fix [BUG] API Error 400 - MCP tool schema uses oneOf/allOf/anyOf at top level [1 comments, 2 participants]

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anthropics/claude-code#56174•Fetched 2026-05-05 05:56:15
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Error Message

API Error: 400 { "type": "error", "error": { "type": "invalid_request_error", "message": "tools.68.custom.input_schema: input_schema does not support oneOf, allOf, or anyOf at the top level" }, "request_id": "req_011CaiZnfWRMz6iht1ztGqsn" }

Code Example

API Error: 400
  {
    "type": "error",
    "error": {
      "type": "invalid_request_error",
      "message": "tools.68.custom.input_schema: input_schema does not support oneOf, allOf, or anyOf at the top level"
    },
    "request_id": "req_011CaiZnfWRMz6iht1ztGqsn"
  }
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Preflight Checklist

  • I have searched existing issues and this hasn't been reported yet
  • This is a single bug report (please file separate reports for different bugs)
  • I am using the latest version of Claude Code

What's Wrong?

Getting error when starting a conversation with MCP servers enabled:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error", "message":"tools.68.custom.input_schema: input_schema does not support oneOf, allOf, or anyOf at the top level"},"request_id":"req_011CaiZnfWRMz6iht1ztGqsn"}

Steps to reproduce:

  1. Enable Meta Ads MCP integration on claude.ai
  2. Open Claude Code desktop app (Windows)
  3. Start any conversation

Expected: Conversation starts normally Actual: API 400 error blocks all conversations

The issue appeared after enabling the Meta Ads MCP server. Request ID: req_011CaiZnfWRMz6iht1ztGqsn

<img width="925" height="463" alt="Image" src="https://github.com/user-attachments/assets/cef4b173-b1c0-4771-8a95-92ebf1ce5061" />

What Should Happen?

Conversation starts normally without any API errors.

Error Messages/Logs

API Error: 400
  {
    "type": "error",
    "error": {
      "type": "invalid_request_error",
      "message": "tools.68.custom.input_schema: input_schema does not support oneOf, allOf, or anyOf at the top level"
    },
    "request_id": "req_011CaiZnfWRMz6iht1ztGqsn"
  }

Steps to Reproduce

  1. Enable Meta Ads MCP integration on claude.ai
  2. Open Claude Code desktop app (Windows)
  3. Start any conversation

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

Unknown

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

The error occurs with all MCP servers enabled (Meta Ads, Ahrefs, Canva, Figma, Gmail, Google Calendar, Google Drive, HubSpot, Klaviyo, Make, Motion, Notion, Slack, Supermetrics, Tavily, etc.).

The issue started after enabling the Meta Ads MCP integration. Disabling all MCP integrations resolves the error.

The error references tools.68, suggesting the 68th tool in the list has an invalid input_schema using oneOf, allOf, or anyOf at the top level, which is not supported by the Anthropic API.

extent analysis

TL;DR

Disable the Meta Ads MCP integration or update the input schema of the 68th tool to remove oneOf, allOf, or anyOf at the top level.

Guidance

  • Verify that the issue is resolved by disabling the Meta Ads MCP integration, as mentioned in the Additional Information section.
  • Check the input schema of the 68th tool (likely Meta Ads) for anyOf, oneOf, or allOf at the top level and update it to a supported format.
  • Test the conversation startup with other MCP servers enabled to ensure the issue is specific to the Meta Ads integration.
  • If the issue persists, try to identify the exact version of Claude Code being used, as the problem may be version-specific.

Example

No code snippet is provided, as the issue seems to be related to the configuration of the MCP integration rather than a code error.

Notes

The error message suggests that the issue is related to the input schema of the 68th tool, which is likely the Meta Ads integration. Disabling this integration resolves the error, indicating that the problem is specific to this tool.

Recommendation

Apply workaround: Disable the Meta Ads MCP integration until the input schema issue is resolved, as this is a non-intrusive solution that allows conversations to start normally.

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claude-code - 💡(How to fix) Fix [BUG] API Error 400 - MCP tool schema uses oneOf/allOf/anyOf at top level [1 comments, 2 participants]