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

The description discloses that the body is discarded, implying a read-only operation with no side effects, which is valuable given there are no annotations. However, it does not explain behaviors for other parameters (e.g., whether URL, city, or host are validated, normalized, or discarded) and provides no information about error handling, return format, or rate limits. The single behavioral fact is helpful but incomplete for a tool with such a broad 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 a single concise sentence, which is efficient, but it is under-specified and does not front-load critical information about the tool's full scope. It is not poorly structured, but it lacks the detail needed to be effective. The brevity is a positive, but it sacrifices clarity and completeness.

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 nine parameters and no output schema, the description is severely incomplete. It only addresses the JSON validation case, leaving the purpose and usage of the other eight parameters unexplained. An agent would struggle to know what to pass for 'url', 'city', or 'zone', or whether these are validated similarly. The description does not adequately cover the tool's actual capabilities, making it inadequate for reliable invocation.

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?

Schema description coverage is 100%, so the baseline is 3. The description adds no parameter-level meaning beyond what the schema already provides. It mentions 'body' but no parameter is named 'body'; the closest is 'json', whose schema description already says 'JSON text to validate; discarded after the check'. The description does not clarify the roles of the other eight parameters, so it does not enhance understanding beyond the schema.

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 a specific verb and resource ('Check whether a body is valid JSON') but the input schema contains 9 parameters with a wide range of purposes (URL, city, feed, host, path, zone, query) that are not mentioned. The name 'validate-json' reinforces the JSON focus, but the broad schema suggests the tool is more general, so the purpose is ambiguous and does not clearly distinguish it from sibling validators like 'domain-shape' or 'file-path-ok'.

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 such as 'domain-shape', 'file-path-ok', or 'fetch-status'. The description does not mention any exclusions or conditions. An agent must infer usage solely from the name, which is insufficient for a tool with nine parameters that likely cover multiple validation scenarios.

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