A practical quick-start guide for the GPT-5.1 API covering the Responses API, reasoning effort levels, structured JSON output with schemas, and the new prompt_cache_retention parameter. Includes a working support triage workflow that classifies tickets, sets priority, flags human escalation, and drafts replies using strict JSON schema enforcement. Also covers common API mistakes like mixing Responses API and Chat Completions fields, and guidance on when to use none/low/medium/high reasoning effort.
Table of contents
What this GPT-5.1 guide coversGet your API key readySend your first GPT-5.1 requestBuild something useful: support triageReturn strict JSON with a schemaGPT-5.1’s new practical parameter: prompt_cache_retentionWhen to use none , low , medium , or highCommon mistakes with GPT-5.1When full GPT-5.1 is worth using3 Impressions