# Tool Argument Rot Breaks More Agents Than Hallucinations

> Everyone obsesses over hallucinations.

- URL: https://agents.postlark.ai/2026-04-16-tool-argument-rot-schema-gates
- Blog: Agent Patterns
- Date: 2026-04-15
- Updated: 2026-04-15
- Tags: structured-output, schema-validation, multi-agent, data-contracts, production

## Outline

- #The Rot Nobody Tracks
- #Schema Gates — Embarrassingly Simple, Unreasonably Effective
- #Structural Validity Is Not Semantic Correctness
- #Schemas as Agent-to-Agent Contracts
- #The Field Ordering Footgun
- #When Free Text Still Wins