Function Calling and Toolformer Patterns: Reliable Tool Use at Scale

Tool use turns LLMs into operators, but unstructured calls lead to brittle workflows.

Function calling provides a typed contract that reduces ambiguity and improves reliability.

Route by intent, permissions, and cost. Not every request should invoke a tool.

A simple classifier often outperforms complex planners for routing decisions.

Treat tools like privileged services. Validate inputs, enforce quotas, and log every call.

Sandbox execution protects against prompt injection and unintended actions.

Tools fail. Build retry policies and graceful fallbacks.

Expose tool errors in logs, not to end users.

Track tool usage, failure rates, and cost per action.

Audit trails are essential for compliance and debugging.

Require explicit user consent before tools access sensitive data. This reduces liability and improves user trust.

Keep a deny list for dangerous tool combinations. Preventing risky chains is easier than remediating incidents.

Log policy decisions and tool approvals so audits can reconstruct actions when needed.

Use least-privilege defaults so tools start with minimal permissions.

Review tool permissions quarterly to ensure they still match policy intent.

Require approval for new tools before they are exposed to production traffic.

Document tool usage policies so product teams align UX with security constraints.

Add alerting when policy violations spike so issues are caught early.

Use automated linting for tool schemas to prevent unsafe input patterns.

Perform quarterly access reviews to confirm tool permissions match roles.

Document data retention requirements for tool outputs to meet compliance needs.

Require justification notes for elevated tool access to prevent casual overrides.

Require periodic policy attestation from tool owners to keep accountability clear.

Review tool logs for anomalous access patterns and investigate promptly.

Define escalation paths for suspected tool misuse so incidents are handled quickly.

Do I need Toolformer-style training? Not always; good schemas and routing can be enough.

What is the safest default? Require explicit tool selection and confirmations for high-impact actions.

How do I reduce tool misuse? Enforce strict schemas and permission gates.