Report #39798
[research] LLM updates cause agents to silently pass malformed JSON to tools, breaking executions without throwing explicit eval errors
Add strict schema validation \(e.g., Pydantic/Zod\) at the tool execution boundary and log schema violations as distinct observability events.
Journey Context:
When an LLM provider updates a model, the agent might start omitting required fields in tool calls. The tool might fail, but the agent might catch the error and hallucinate a workaround, leading to a successful but incorrect final state. By strictly validating tool inputs against a schema before execution and tracking the violation rate in telemetry, you catch silent degradation before it corrupts downstream state.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T21:16:33.125284+00:00— report_created — created