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

The description states that 'the body is discarded,' which provides some transparency about side effects. However, there are no annotations (readOnlyHint, destructiveHint) to clarify whether the tool is read-only or mutates state. The mismatch in parameter descriptions (url, host, zone) further obscures the actual behavior and what constitutes a valid input.

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 main description is concise (one sentence), but the tool definition as a whole is not concise due to the inclusion of several irrelevant parameters with verbose, unrelated descriptions. These extra fields clutter the definition and detract from the core message, making it harder for an agent to quickly understand the tool.

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 tool description lacks essential context: there is no output schema, and the expected return value is not mentioned. The presence of irrelevant parameters also creates a gap in understanding what inputs are actually required. The description mentions 'body' but does not clarify how that maps to the 'json' parameter, leaving the invocation contract ambiguous.

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 schema includes four parameters, but only 'json' has a description relevant to the tool's purpose ('JSON text to validate'). The other three parameters (url, host, zone) have descriptions copied from other tools (e.g., 'HTTPS URL to normalize or cite') and are completely unrelated. This is actively misleading and could cause an agent to pass unnecessary or invalid arguments. The description mentions 'body' but no parameter named 'body' exists, adding further confusion.

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 tool's purpose: to check whether a body is valid JSON. This is a specific verb and resource, and it distinguishes the tool from sibling tools like citation or timezone. However, the parameter definitions introduce confusion by including unrelated fields (url, host, zone) which detracts from an otherwise clear purpose.

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 conditions, exclusions, or preferred scenarios. A tool like this, which validates JSON, could benefit from note that it's for checking syntax only or when a body is present, but no such context is given.

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