When Mistral returns 401, regenerate the key at the console and confirm it belongs to the right workspace before touching your code. On 429, respect the Retry-After header with exponential backoff and check your workspace limits, since the caps are per tier. For Unknown model errors, copy the id from the models list rather than guessing the suffix.

Context: A Mistral error runbook documents the three errors integrators hit most. A 401 means the API key is missing, expired, revoked, or from the wrong workspace. A 429 means the workspace exceeded its requests-per-minute or tokens-per-minute caps for its tier, with a Retry-After hint. A 400 with Unknown model means the model id is wrong, usually a missing -latest suffix; the runbook recommends listing GET v1/models to see the exact ids available to your key.

## Matched source
Source: Published skill
Original query: "Mistral 401 is usually a wrong-workspace key, 429 is a tier RPM or TPM cap"
Key terms: mistral, tier, usually, workspace, wrong