Codex CLI with a custom provider: an agent without a token bill

Why connect it

Codex CLI supports third-party providers in ~/.codex/config.toml. Tenzo Cloud is added as its own provider, so switching back takes one line.

The key lives in an environment variable rather than the file, so it will not end up in a commit by accident.

How to connect Codex CLI

You need a key from the dashboard: 3 free hours start right after sign-up. Replace tc-your-key with your key.

1. 1

   Get a key

   Create a key in the dashboard under API keys.

2. 2

   Store the key in a variable

   Add TENZO_API_KEY to your environment or to ~/.zshrc / ~/.bashrc.

   terminalCopy

   export TENZO_API_KEY=tc-your-key

3. 3

   Add the provider

   Open ~/.codex/config.toml (create it if needed) and add the block below.

   ~/.codex/config.tomlCopy

   model = "glm-5.3"
   model_provider = "tenzo"
   
   [model_providers.tenzo]
   name = "Tenzo Cloud"
   base_url = "https://tenzo-cloud.com/v1"
   env_key = "TENZO_API_KEY"
   wire_api = "responses"

4. 4

   Run codex

   Codex now works through Tenzo Cloud with the chosen model.

Common errors and fixes

Codex complains the key is missing

TENZO_API_KEY is not set in the current terminal. Run export and restart codex.

401 invalid_api_key, “key not found”

Make sure the whole key is copied with no spaces or quotes and is enabled in the dashboard. Expired keys also return 401.

403 no_access, “no access to this model”

There is no active subscription for this model, or the key does not allow this model or your IP. Check Plans and the key restrictions in the dashboard.

404 model_not_found

The model id is wrong. Use an id from the model list, for example qwen-3.8-max or glm-5.3.

429 concurrency_limit

All your streams are busy or you exceeded 120 requests a minute. Retry in a few seconds or buy more streams, they stack.

503 model_unavailable

The model is under maintenance. Each model’s status is on the status page; switch models with one line.