Building AI Assistants With APIs

An Assistant Is an Application, Not Just a Chat Box

API-based assistants combine model calls, system instructions, user state, retrieved context, tool access, output validation, storage, logging, and UI behavior. Treat the assistant as an application layer with explicit boundaries.

Core Design Areas

• Conversation state, memory rules, and user/session identity.
• Context construction from retrieval, files, app state, and user input.
• Tool routing for search, database lookup, app actions, and workflow triggers.
• Streaming and latency design for good user experience.
• Evaluation suites for regression, safety, tool use, and task completion.

Separate Reasoning From Action

Assistants should often reason, draft, or recommend before taking irreversible actions. Use approval gates for messages, writes, purchases, deletions, permission changes, or external side effects.