Function Calling and the Architecture of Useful Agents

Short summary

Function calling is the structured protocol letting LLMs request external actions by outputting specifications rather than executing code directly. Quality depends on tool definitions—unambiguous names, trigger-condition descriptions, and explicit schemas. Production agents need parallel-call optimization, robust error handling with retries, and identity preservation.

• •Function calling is the protocol that lets agents interact with external systems—not a nice-to-have, but essential to usefulness.
• •Tool definition quality (names, descriptions, schemas) determines agent reliability far more than model capability.
• •Production agents need three patterns: retry logic for transient failures, structured error reporting, and fallback paths when tools fail.

Generated with AI, which can make mistakes.