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

There are no annotations, so the description must carry the full burden of behavioral disclosure. It does disclose that 'the body is discarded,' which is a useful side-effect note. However, it does not explain what the tool returns (e.g., boolean, error message), nor does it clarify which parameter constitutes 'the body.' This ambiguity undermines transparency.

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 exceptionally short—two sentences with no filler. It front-loads the primary action and includes a behavioral note. However, its brevity sacrifices critical information, so it earns a 4 for conciseness but not a 5 because it omits necessary context.

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 optional parameters, no output schema, and no annotations, the description is severely incomplete. It does not explain what happens to the other eight parameters (e.g., ref, url, city) or whether they are ignored. The tool's actual behavior beyond JSON validation is unclear, making it difficult for an agent to call 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?

While the input schema provides 100% coverage with descriptions for each parameter, the tool description adds no value by rephrasing them. It uses the vague term 'body' without linking it to the 'json' parameter, which is the only one relevant to JSON validation. The schema itself is informative, but the description fails to leverage or clarify the relationship, leaving the agent uncertain about which fields matter.

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 tool's core function: checking whether a body is valid JSON. It uses a specific verb ('check') and resource ('body is valid JSON'), making the purpose understandable. However, it does not explicitly differentiate from sibling validators like 'domain-shape' or 'fetch-status', but the name 'validate-json' is self-explanatory enough to stand out.

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 gives no guidance on when to use this tool versus alternatives. It does not mention prerequisites, typical use cases, or situations where another validator would be more appropriate. With 28 sibling tools, the lack of routing or context leaves 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.