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

No annotations are provided, so the description carries the transparency burden. It does disclose one useful behavioral trait, that values are discarded, but it does not clarify whether nested keys are counted, whether the operation has side effects on any memory state, or how empty or invalid input is handled.

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 eight words in two front-loaded sentences, with no filler or repetition. Every word contributes to explaining what the tool computes and what it ignores.

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 and no annotation coverage, and the description does not explain how to select from the nine optional parameters, what count semantics apply, or what the response looks like. The definition is not complete enough for confident invocation without further inference.

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 descriptions cover all parameters, but the tool description adds no parameter mapping. The only parameter mentioning JSON is described as 'JSON text to validate; discarded after the check', which suggests validation rather than counting, and it is unclear whether the agent should pass serialized JSON or use the top-level argument object itself.

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 precise operation: count keys in a JSON object, with the additional qualifier that values are discarded. This verb+resource pairing clearly separates it from sibling validation and shape-check tools.

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?

The use case is implied by the purpose, but there is no explicit when-to-use/when-not-to-use guidance and no alternative tool is named. An agent must infer that this tool is for obtaining a key count rather than for validation, normalization, or other sibling operations.

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