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

No annotations are provided, so the description must carry the full behavioral burden. It only mentions that values are discarded, but does not clarify side effects (e.g., whether it is read-only), error handling, or what happens with invalid JSON. The minimal statement adds little beyond the name.

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 a single concise sentence with no wasted words. It is appropriately short for the simplicity of the operation, though it could be slightly more informative without becoming verbose.

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?

For a tool with 9 parameters, no annotations, and no output schema, the description is severely under-specified. It does not explain the return value (the count), how to pass the JSON, or how to handle multiple inputs. An agent would have to infer too much.

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 input schema has 100% coverage, so each parameter is described in the schema itself. The description does not add extra meaning, such as clarifying that the 'json' parameter is the primary input or how other parameters relate. Baseline 3 is appropriate given high schema coverage, but the description could have helped identify the relevant parameter.

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 clear action (count keys) on a specific resource (a JSON object) and notes that values are discarded. It is not a tautology and distinguishes the core operation, though it does not explicitly differentiate from sibling tools like validate-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 guidance is given on when to use this tool versus alternatives. The description does not mention which parameter to use (e.g., 'json') or any context that would help an agent decide when to call it. With 9 parameters and 0 required, the lack of usage direction is a significant gap.

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