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

The description mentions 'The body is discarded' but gives no explanation of what happens to the input or what side effects occur. There are no annotations to clarify read-only or destructive behavior, and the phrase 'discarded after the check' is ambiguous.

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 extremely brief but fails to convey essential information. It is not concise in a useful way; it omits critical details and introduces irrelevant parameters without clarification, making the text more confusing than helpful.

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 9 parameters and no output schema, the description provides almost no context. It does not explain the expected input format, return value, error conditions, or how the parameters relate to the tool's function. The description is grossly incomplete for an agent to use correctly.

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?

Although the schema covers all parameters, the descriptions are nonsensical in the context of JSON validation. For example, 'ref' is described as 'Git ref name; discarded after the shape check', and 'city' as 'City name for a public weather hint'—these have no obvious relation to validating JSON. The meaning of 'json' is also unclear since it duplicates the tool's primary action.

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 description states 'Check whether a body is valid JSON' but never defines what 'body' means. The parameter list includes unrelated fields like 'ref', 'url', 'city', and 'query', which are not explained in the context of JSON validation. This creates confusion about the tool's actual purpose.

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?

No guidance is provided on when to use this tool versus alternatives like 'browser-url-ok' or 'fetch-status'. The description gives no conditions for invocation or exclusions, leaving the agent to guess.

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