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

With no annotations, the description carries the burden and does disclose a useful behavioral trait: 'The body is discarded.' However, it omits the return value/format and error behavior, so transparency is partial.

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?

Two short sentences front-load the action and contain no filler. The description is appropriately brief for a straightforward validator.

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?

The description is incomplete for the 7-parameter schema: it never identifies the 'json' parameter as the body to validate, and it does not state the result format. The unrelated-looking parameters (ref, url, city, feed, host, path) could confuse an agent, and there is no output schema to fill the gap.

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?

Every property in the input schema has its own description (100% coverage), so the baseline is 3. The main description adds no parameter detail beyond calling the input a 'body,' but the schema provides the necessary parameter meanings.

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 uses a specific verb and resource: 'Check whether a body is valid JSON.' It clearly states the tool's core function, though it does not explicitly distinguish it from sibling shape/validation tools.

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 when-to-use guidance or alternatives are provided; the description gives no prerequisites, exclusions, or conditions. The intended use is only implied by the tool name and the one-line action.

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