Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and idempotencyHint, so the safety profile is covered. The description adds the useful no-retention detail that the body is discarded, but it does not address what happens for invalid JSON or which inputs are ignored; the boolean output is supplied by the output schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two short sentences with the core action front-loaded and no filler. Each sentence earns its place: one for purpose, one for data-handling behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With annotations covering side effects and output_schema covering return type, the description is nearly complete for a simple validation tool. The main gap is the absence of an explicit pointer to the json parameter among the seven schema properties, but the schema description for json fills that gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

All seven schema parameters have individual descriptions, so schema coverage is effectively 100% and the baseline is 3. The description's generic 'body' does not map explicitly to the json parameter or clarify the unused parameters, but the schema already describes json as the text to validate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The first sentence, 'Check whether a body is valid JSON,' states the action, object, and validation criterion precisely. It is not a tautology and is easy for an agent to act on, though it does not explicitly differentiate from sibling validators/shape tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no guidance about when to choose validate-json over sibling tools, no explicit conditions, and no 'when not to use' note. The only additional sentence, 'The body is discarded,' describes a behavior rather than usage.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.