MCP tool schemas can include unsupported OpenAI JSON Schema keywords #32488

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1. github-actions

   assigned

   kitlangton

   on Jun 16, 2026
2. github-actions commented on Jun 16, 2026

   

   github-actionsBot

   on Jun 16, 2026 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • GPT-5.5 tool calls fail with Backstage MCP pattern schemas #30553: GPT-5.5 tool calls fail with Backstage MCP pattern schemas — same root cause: MCP tool schemas containing JSON Schema keywords (e.g. pattern) that OpenAI's API rejects, causing requests to fail before tool execution.
   • Gemini schema sanitizer doesn't strip contentEncoding from MCP tool schemas #15408: Gemini schema sanitizer doesn't strip contentEncoding from MCP tool schemas — same class of problem (provider-specific schema sanitization needed) but for the Gemini provider.

   If your issue is specifically about the OpenAI provider not stripping unsupported keywords, it may overlap significantly with #30553.
3. rekram1-node

   marked GPT-5.5 tool calls fail with Backstage MCP pattern schemas #30553 as a duplicate of this issue on Jun 16, 2026
4. rekram1-node

   marked Bug: Invalid JSON Schema Generated Due to Unsupported Regex Lookaround in fileKey Pattern On GPT 5.5 #31996 as a duplicate of this issue on Jun 16, 2026
5. rekram1-node

   marked GPT 5.5 #32073 as a duplicate of this issue on Jun 16, 2026
6. rekram1-node

   marked "Invalid schema for function" in google-docs-mcp #20273 as a duplicate of this issue on Jun 16, 2026
7. rekram1-node

   closed this as completedon Jun 18, 2026