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

With no annotations provided, the description carries the burden of behavioral disclosure. It does state 'The body is discarded,' which clarifies that the tool has no persistent side effects. However, it does not explain the return value (e.g., boolean, error) or any error handling, leaving a significant behavioral gap.

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 short and front-loaded with the core purpose, but it is under-specified. It omits critical information such as return behavior and parameter selection. The brevity is not balanced with completeness, so it is more a case of under-specification than effective conciseness.

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 tool with no output schema and no annotations, the description should clarify the expected input and output. It does not state what the tool returns (e.g., a boolean, success/failure), nor does it address the extraneous parameters in the schema. The agent cannot reliably call this tool correctly without guessing.

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 schema has 100% description coverage, the parameter descriptions are generic and unrelated to JSON validation (e.g., 'HTTPS URL to normalize or cite' for 'url'). The tool description mentions a 'body' but does not explicitly map it to the 'json' parameter or clarify that the other three parameters (url, host, zone) are irrelevant. This creates confusion and fails to compensate for the schema's misleading context.

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 a specific action: 'Check whether a body is valid JSON.' It identifies the resource (JSON body) and the verb (check). It does not explicitly differentiate from sibling tools, but the tool's purpose is distinct from siblings like 'normalize-url' or 'iana-zones', so an agent can infer its role without ambiguity.

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 provides no guidance on when to use this tool versus alternatives. It does not mention any prerequisites, exclusions, or comparison to sibling tools. An agent is left to infer usage from the tool name and minimal description, which is insufficient for clear selection.

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