openai / openai/codex

MCP codex_apps: Selected model is at capacity recurring error with available quota

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bug mcp tool-calls
Dominant language
Rust
Stars
125k
Forks
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PR merge metrics
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Description

What version of Codex CLI is running?

codex-cli 0.153.4

What subscription do you have?

plus

Which model were you using?

No response

What platform is your computer?

No response

What terminal emulator and version are you using (if applicable)?

No response

Codex doctor report

What issue are you seeing?

Describe the bug

Consistently get error:
Selected model is at capacity. Please try a different model.

This happens during MCP initialize / tool call phase against endpoint:
https://chatgpt.com/backend-api/ps/mcp

My account still has remaining Codex subscription quota, it is NOT quota exhaustion or rate‑limit reached.
The error occurs frequently even under low request frequency.

This is MCP client scenario(codex_rmcp_client), not official codex desktop/cli.

Reproduction steps

  1. Start MCP codex_apps server
  2. Send initialize request
  3. Receive capacity error response

Expected behavior

MCP session initialize normally, without capacity rejection when quota remains.

What steps can reproduce the bug?

Uploaded thread: 01a08056-c137-76a3-92d7-e93d0861e582

What is the expected behavior?

No response

Additional information

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the codex_rmcp_client MCP initialize and tool-call flow, then review the uploaded thread 01a08056-c137-76a3-92d7-e93d0861e582. Reproduce against https://chatgpt.com/backend-api/ps/mcp using codex-cli 0.153.4 and a Plus account with remaining quota. Done means the recurring capacity rejection is reproduced and its handling is corrected or clearly isolated.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
api, backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Needs clarification
Newbie friendliness
38/100

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