[GH-ISSUE #245] issue: enums not present in Open API schema #113

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opened 2026-10-18 21:11:53 +00:00 by bsakaguchi · 0 comments

bsakaguchi commented

2026-10-18 21:11:53 +00:00

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Originally created by @faevourite on GitHub (Sep 7, 2025).
Original GitHub issue: https://github.com/open-webui/mcpo/issues/245

Check Existing Issues

I have searched the existing issues and discussions.
I am using the latest version of mcpo.

mcpo Version

v0.0.17

Open WebUI Version (if applicable)

v0.6.26

Operating System

MacOS Sequoia, Docker

Browser (if applicable)

No response

Confirmation

I have read and followed all instructions in README.md.
I am using the latest version of both MCPO and Open WebUI.
I have included the browser console logs.
I have included the Docker container logs.
I have listed steps to reproduce the bug in detail.

Expected Behavior

Enums listed in MCP field spec to show up in the converted OAI spec

Actual Behavior

No enum restrictions in OAI spec, just a plain string.

Steps to Reproduce

Use an MCP server that uses enums to constrain field values. I tried with Readwise MCP. Here's where it defines enums.
Check swagger json for the server and note that enums are missing.

Logs & Screenshots

Schema in MCP Inspector

No schema in MCPO

Additional Information

LLMs can get easily confused without enums info. For the Readwise MCP server, asking something simple like "search my readwise highlights for MCP" results in models guessing the field_name incorrectly (e.g. gemini tried "highlight_content").

Originally created by @faevourite on GitHub (Sep 7, 2025). Original GitHub issue: https://github.com/open-webui/mcpo/issues/245 ### Check Existing Issues - [x] I have searched the existing issues and discussions. - [x] I am using the latest version of mcpo. ### mcpo Version v0.0.17 ### Open WebUI Version (if applicable) v0.6.26 ### Operating System MacOS Sequoia, Docker ### Browser (if applicable) _No response_ ### Confirmation - [x] I have read and followed all instructions in `README.md`. - [x] I am using the latest version of **both** MCPO and Open WebUI. - [x] I have included the browser console logs. - [x] I have included the Docker container logs. - [x] I have listed steps to reproduce the bug in detail. ### Expected Behavior Enums listed in MCP field spec to show up in the converted OAI spec ### Actual Behavior No enum restrictions in OAI spec, just a plain string. ### Steps to Reproduce 1. Use an MCP server that uses enums to constrain field values. I tried with [Readwise MCP](https://github.com/readwiseio/readwise-mcp). [Here's where it defines enums](https://github.com/readwiseio/readwise-mcp/blob/master/src/index.ts#L64-L69). 2. Check swagger json for the server and note that enums are missing. ### Logs & Screenshots ## Schema in MCP Inspector <img width="1582" height="1220" alt="Image" src="https://github.com/user-attachments/assets/755bf881-6f7c-4ee0-b41f-a7011e933c55" /> ## No schema in MCPO <img width="1046" height="438" alt="Image" src="https://github.com/user-attachments/assets/0a73db27-09cc-48e7-bc04-17af4ccfa8ef" /> ### Additional Information LLMs can get easily confused without enums info. For the Readwise MCP server, asking something simple like "search my readwise highlights for MCP" results in models guessing the `field_name` incorrectly (e.g. gemini tried "highlight_content").

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2026-10-18 21:11:53 +00:00