Tool Contracts as Deterministic API Boundaries
Explore how defining tool contracts creates deterministic API boundaries that govern safe tool usage, enforce least privilege, and support idempotency for reliable AI operations. Understand structured validation, error handling, and evidence production to maintain security and auditability within agent containment.
A tool is treated as an API product with deterministic behavior guarantees. For the case review assistant, that decision separates safe reads via SearchPolicy and GetCase from unsafe writes via CreateCase, UpdateCaseStatus, or NotifyManager that can duplicate or corrupt the system of record when retries and partial failures occur.
Tool contracts sit inside the agent containment envelope as the enforcement substrate that makes least privilege and approvals meaningful. The envelope limits what tools can be called and under what conditions. The tool contract defines what it means to call each tool successfully, what counts as a failure, and what evidence the call produces for audit and incident review. Without that boundary, write tools drift into ambiguous behavior: best-effort updates, natural-language error strings, hidden side effects nobody can govern.
Minimum fields in a tool contract
A minimum tool contract starts with strict input and output schemas, machine-validated at the boundary. Give the schema types, required fields, ...