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

Even with no annotations to rely on, the description discloses a meaningful behavioral trait—that the input body is discarded after the check—which is valuable for an agent to know before invoking the tool. It does not explicitly state side effects, but the discard statement effectively communicates the non-persistent nature of the operation.

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 concise and well-structured: two short sentences that front-load the core purpose and then add the key behavioral detail. There is no filler or repetitive content.

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 plus the fully covered schema is adequate for a simple validation tool, but the absence of an output schema means the description should have clarified what is returned (e.g., a boolean, an error, or a status code). Given zero annotations, this is a meaningful gap, though not severe.

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 coverage is 100%, so all four parameters are already documented in the input schema. The description adds important semantic context for the 'json' parameter by stating that it is 'discarded after the check', which clarifies its lifetime and purpose beyond the schema's generic 'JSON text to validate'.

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 the specific verb phrase 'Check whether a body is valid JSON' to establish the tool's purpose as a validation operation, and explicitly states 'The body is discarded' to clarify its side-effect scope. It is well-differentiated from the sibling tools, which are oriented toward URL/host/timezone normalization and citation, though it doesn't name them.

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 straightforward, one-shot validation use case, but provides no explicit 'when to use' guidance or exclusion cues. It does not reference alternatives or warn against misuse, leaving some judgment to the agent.

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