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

The description says values are discarded but does not disclose any side effects, permissions, rate limits, or whether the tool is read-only. With no annotations provided, the description carries the full burden and does not satisfy it.

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 extremely concise: two short sentences with no redundant wording. It is well-structured for a minimal tool description.

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 is contextually incomplete: it has nine unrelated optional parameters, no output schema, and no explanation of how to invoke it or what the counted result looks like. The description does not resolve the mismatch between its stated purpose and the actual schema.

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 defines nine optional string parameters with individual descriptions, but none of them appears to represent a JSON object. No parameter is required and the description does not explain how these parameters relate to 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 the action 'Count keys in a JSON object' and notes values are discarded, so the basic purpose is somewhat clear. However, the input schema contains no JSON object parameter, making it unclear what input actually represents the object.

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 use this tool, how to supply the JSON object, or which of the nine optional parameters should be provided. No alternatives are mentioned.

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