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 and behavior. It mentions that values are discarded, but it does not state whether the operation is read-only, what errors may occur, or what happens with invalid JSON.

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 free of fluff, containing only the core action and a note about values. It is efficient, though it omits important context.

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 has nine parameters and no output schema, but the description does not explain expected input, output, errors, or which parameters are relevant. The description is too thin for an agent to use the tool confidently.

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?

Although every parameter has a schema description, the tool description does not clarify which parameter is the JSON object or how the many unrelated parameters (ref, url, city, feed, host, path, zone, query) relate to counting keys. The wording 'discarded after the check' on json conflicts with the stated purpose of counting keys.

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 in a JSON object'—and adds that values are discarded. This distinguishes it from a validation or normalization tool, though it does not explicitly differentiate it from sibling tools such as 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 provided about when to choose this tool over alternatives, what input is expected, or how the result should be used. The description only states the action and gives no context for selection.

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