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

The description discloses that the body is discarded, which is a behavioral trait. However, it does not mention side effects beyond that (e.g., whether it validates against a schema, returns a boolean, or throws errors). Without annotations, this partial disclosure is somewhat helpful but incomplete.

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 concise—a single sentence that communicates the core purpose without unnecessary words. It is well-structured and easy to parse.

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?

Given the mismatched parameters and lack of clarification on which parameter actually serves as the 'body,' the description is incomplete. It does not explain how the parameters relate to the validation task, leaving ambiguity about required inputs and expected output.

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 provides descriptions for all four parameters, several are clearly mismatched or irrelevant: 'url' is described as 'HTTPS URL to normalize or cite,' 'host' as 'Public hostname,' and 'zone' as 'IANA timezone name'—none of which pertain to JSON validation. Only 'json' has a sensible description. The misleading parameter semantics severely undermine usability.

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 clearly states the primary action ('Check whether a body is valid JSON') and the resource (the JSON body). It is concise and understandable, though the parameter names do not perfectly align with the described resource, slightly reducing clarity.

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?

The description provides no guidance on when to use this tool versus alternatives, nor any prerequisites or conditions. The only hint is 'The body is discarded,' which implies a stateless check, but there is no explicit usage direction.

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