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

The description does disclose a meaningful side effect: 'The body is discarded.' Without annotations, the description carries the burden, but it does not state whether the tool returns a boolean, an error, or nothing, nor what happens for invalid JSON.

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: two short sentences with no filler. The primary purpose is front-loaded, followed by the key side effect.

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?

For a simple validator, the core operation is stated, but the description does not clarify which parameter represents the 'body' or how the result is conveyed. The mismatched schema properties create enough ambiguity that more context would help, especially given there is no output schema.

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 input schema gives each parameter a description, so schema coverage is 100%. The description itself adds no parameter-level meaning, and 'body' is not mapped to a named parameter. The presence of seemingly unrelated properties like `city`, `feed`, and `host` adds confusion without additional explanation.

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 clear action and object: 'Check whether a body is valid JSON.' This distinguishes it from the sibling URL/domain/shape-checking tools, which focus on non-JSON formats. However, 'body' is not explicitly mapped to the `json` input parameter, so a slight ambiguity remains.

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?

Usage is implied by the name and description: use this tool when you need to validate JSON. No alternatives or when-not-to-use conditions are stated, and no guidance is given about the other schema fields such as `url`, `city`, or `feed`.

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