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

There are no annotations, so the description carries the full transparency burden. It discloses that the body is discarded, which addresses privacy and non-retention. However, it does not state the expected output (e.g., boolean, error message), behavior on malformed JSON, or whether the operation is read-only in a broader sense.

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 only two sentences and front-loads the core purpose in the first. Every word earns its place, and it is free of fluff. It is, however, arguably too terse given the eight-parameter schema, which could warrant a bit more orientation.

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 no annotations and no output schema, the description must supply full context, but it leaves key gaps: no mention of return format, no mapping to the input schema's many unrelated parameters, and no mention of error behavior. The 'discarded' note is helpful, but the agent still cannot confidently determine how to invoke the tool correctly or interpret the result.

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?

The schema lists eight parameters, each with a description, so schema coverage is high; the baseline would normally be 3. But the description does not clarify that only the 'json' parameter is relevant—the other parameters (url, city, feed, host, path) appear unrelated to JSON validation and may confuse an agent. The description's 'body' language also does not explicitly map to the 'json' parameter, adding no semantic value 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.' It is clearly distinct from sibling shape-check tools like domain-shape, browser-url-ok, or wiki-title-ok, which validate URL, domain, or title forms rather than JSON syntax. The tool name reinforces the 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?

The description implies a use case—validating JSON—but gives no explicit guidance on when to choose this tool over alternatives or when not to use it. It does not mention any of the sibling validators or the conditions that would route an agent here instead.

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