Structured Output Modes Are Quietly Becoming Table Stakes for Agent Tooling

## From Prompt-and-Pray to Guaranteed Schemas Early agent tooling often relied on prompting a model to "respond in JSON" and hoping for well-formed output. That approach is being replaced by constrained decoding and schema validation built into the inference layer itself. ## Why Reliability Matters More as Chains Get Longer A single malformed output in a five-step agent chain can silently corrupt every step after it. As multi-step agent workflows become more common, the cost of an occasional malformed response compounds fast enough that teams treat guaranteed-valid structured output as a hard requirement. ## The Result Frameworks and APIs that don't offer native structured-output guarantees are increasingly seen as a liability for anything beyond a single-turn chatbot.