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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does mention 'The body is discarded,' which is a behavioral trait, but it doesn't describe return values, side effects (or lack thereof), error handling, or whether the tool is read-only. For a validation tool, this is insufficient.

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. However, it is under-specified and doesn't structure information about the tool's usage or parameters. It lacks front-loaded context, making it minimal but not well-structured for an agent.

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?

Given the tool has 9 optional parameters, no output schema, and no annotations, the description is incomplete. It doesn't explain how parameters relate to validation, which one represents the 'body,' or the tool's expected behavior. An agent would be left guessing how to invoke it correctly.

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%, and each parameter has a description noting it is 'discarded after' its check. This adds meaning beyond the parameter name. The main description adds no parameter-level detail, but since the schema already handles semantics well, a baseline 3 is appropriate.

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 the core action: 'Check whether a body is valid JSON.' This distinguishes it from sibling shape-checking tools (e.g., 'domain-shape', 'file-path-ok') by the specific JSON focus. However, 'body' is ambiguous – it doesn't specify which parameter holds the JSON, though the overall purpose is evident.

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 doesn't mention exclusions, prerequisites, or contextual conditions. The sibling tools cover different validation domains, but the description doesn't explicitly route agents to the correct choice.

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