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

No annotations are provided, so the description must fully disclose behavior. It only says 'Values discarded,' which is minimal. It does not clarify whether the tool reads from URLs, files, or strings, what side effects exist, or what the return value is. For a tool with zero annotation coverage, this is severely under-disclosed.

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 only two sentences, which is concise, but it is under-specified rather than efficiently informative. It omits crucial details about how to invoke the tool and what to expect, so brevity does not contribute to 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?

With 9 parameters, no output schema, and no annotations, the description is grossly incomplete. It does not explain the purpose of the extra parameters, the expected output format, or any operational details. An agent cannot confidently determine how to call this tool correctly 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?

While schema coverage is 100% with each parameter described, the tool description adds no meaning beyond that. It fails to explain how the parameters map to the 'count keys' operation, particularly which parameter holds the JSON object. The parameter descriptions themselves mention 'discarded after the check,' which hints at a validation workflow, but the tool description does not connect this to the counting action.

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 states a specific action ('Count keys in a JSON object') and resource, but it does not align with the 9-parameter schema. Only the 'json' parameter plausibly relates to a JSON object, while the other parameters (ref, url, city, feed, host, path, zone, query) are unexplained and seem unrelated, creating ambiguity about what the tool actually operates on.

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?

There is no guidance on when to use this tool versus the many siblings (e.g., validate-json, domain-shape, normalize-url). No context is given for which scenario calls for counting keys, nor are any exclusions or alternatives mentioned.

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