LiteLLM Proxy Codex CLI Tool Calls Fail — gpt-5-codex Model Returns No Response

What this error means

Codex CLI does not respond correctly when using gpt-5-codex model with tool calls via LiteLLM proxy is a LiteLLM failure pattern reported for developers trying to fix litellm proxy failing with openai codex cli when using gpt-5-codex model with tool/function calls. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #14846: Codex CLI does not respond correctly with gpt-5-codex model via LiteLLM proxy. Simple prompts (e.g., ‘Tell me a poem’) work, but tool call requests (e.g., ‘Explore this repository’) fail. Video evidence provided showing both success and failure cases.

Common causes

• When using LiteLLM proxy with OpenAI Codex CLI and gpt-5-codex model, tool call requests fail while simple prompts work. This indicates a LiteLLM proxy issue with tool/function call routing for the Codex model. Developers need to use LiteLLM as a unified gateway but this blocks Codex CLI workflows.
• GitHub issue #14846: Codex CLI does not respond correctly with gpt-5-codex model via LiteLLM proxy. Simple prompts (e.g., ‘Tell me a poem’) work, but tool call requests (e.g., ‘Explore this repository’) fail. Video evidence provided showing both success and failure cases.

Quick fixes

1. Confirm the exact error signature matches Codex CLI does not respond correctly when using gpt-5-codex model with tool calls via LiteLLM proxy.
2. Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/BerriAI/litellm/issues/14846

Evidence note: GitHub issue #14846: Codex CLI does not respond correctly with gpt-5-codex model via LiteLLM proxy. Simple prompts (e.g., ‘Tell me a poem’) work, but tool call requests (e.g., ‘Explore this repository’) fail. Video evidence provided showing both success and failure cases.

Related errors

• LiteLLM tool call routing error
• OpenAI Codex CLI proxy configuration error

FAQ

What should I check first?

Start with the exact Codex CLI does not respond correctly when using gpt-5-codex model with tool calls via LiteLLM proxy text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed LiteLLM workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Codex CLI does not respond correctly when using gpt-5-codex model with tool calls via LiteLLM proxy.