Why A is the answer

The request-id from the response

Every API response has a request-id header, and the same value appears as request_id in error bodies. Never send your key to anyone.

In detail

• Every API response has a request-id header.
• The same value appears as request_id in error bodies.
• Support can use it to find the call, so never share your key.
• Log the request-id with every call, so it is ready when you need it.

See it in different ways

mindmap
  root((API errors))
    400
      Invalid request
    401
      Bad key
    403
      No access
    429
      Rate limit
    529
      Overloaded

sequenceDiagram
  participant P0 as Your app
  participant P1 as API
  participant P2 as Support
  P0->>P1: Request
  P1-->>P0: Response with request-id
  P0->>P2: Ticket with the request-id

Why the other options are wrong

B. The account password

Support does not need your password, and you should never share it.

C. The model's temperature

Temperature does not identify one specific call.

D. Your API key

An API key is a secret and should never be sent to anyone.

Related questions

• Question 22Your error tracking shows no failures, but some users get no useful answer. The responses are HTTP 200 with stop_reason refusal. What should change?
• Question 14Which order of server-sent events does a streamed Messages response follow?
• Question 15You stream a response that includes a tool call and your JSON.parse throws on every delta. What should the code do instead?
• Question 16A stream started with HTTP 200, then an error event of type overloaded_error arrived partway through. What does your client need?

Learn more

• Our lesson: The API and integration
• Streaming
• Batch processing
• API errors