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

No annotations are present, and the description only says values are discarded. It does not explain behavior on invalid input, return format, or whether side effects occur.

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 front-loaded, but the brevity comes at the expense of necessary details about which parameter holds the JSON object. It is short yet not effectively structured.

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?

There is no output schema, no error semantics, no example, and no clarification of the relationship between the many unrelated parameters and the stated purpose. The tool definition is incomplete for reliable invocation.

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?

Nine optional string parameters are listed, but most appear unrelated to counting JSON keys (ref, url, city, feed, host, path, zone, query). Their descriptions mostly say they are discarded, and the only JSON-related parameter is described as validation, not key counting, so parameters do not clarify the tool's actual input.

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 'Count keys in a JSON object' but does not indicate which input parameter contains that object; the 'json' parameter is described as 'JSON text to validate; discarded after the check', not as the object to count. The purpose is therefore obscured by conflicting schema hints.

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 guidance is given for when to use this tool versus siblings like validate-json or search-query-len. The description provides no usage context, examples, or selection criteria.

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