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

With no annotations, the description carries the burden of explaining side effects, read-only behavior, and output. It only says values are discarded, which gives minimal insight into whether the operation is purely computational or has any external effects.

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 very short and front-loaded, but it is too terse to convey the necessary input mapping or usage context. It has no extraneous words, but the brevity comes at the cost of clarity.

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 9 parameters and no output schema, the description is not contextually complete. It does not explain what the function returns, how to specify the JSON input, or why so many unrelated parameters exist. A user would not be able to confidently invoke this tool from the description alone.

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 descriptions are largely unrelated to the tool purpose. For example, json is described as 'JSON text to validate; discarded after the check' rather than 'the object whose keys will be counted', and many parameters like ref, url, city, and zone have no apparent connection to counting keys. The description does not clarify which parameter is the actual JSON object.

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: count keys in a JSON object and ignore values. This distinguishes it from sibling tools like validate-json, though it does not name the input parameter that holds the JSON.

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 explicit guidance is given about when to use this tool versus alternatives such as validate-json or search-query-len. The description only states what it does, not when it should be preferred or when it should not be used.

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