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

With no annotations provided, the description carries the burden of behavioral disclosure, but it only states that values are discarded. It does not say whether the operation is read-only, how keys are counted (top-level vs nested), what happens on invalid input, or what the return value will be.

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?

Two short sentences with no filler; the action is front-loaded and the discarded-values note earns its place. Nothing could be removed without losing information.

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 annotations, so the description should explain the input source and return format. It leaves ambiguities about parameter mapping, recursion depth, and the result, making it 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?

Schema description coverage is 100%, so parameter details are available in the schema itself and the description need not repeat them. However, the description does not clarify which parameter supplies the JSON object or reconcile the schema's 'json' field saying 'validate' with the tool's counting purpose.

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 names a specific verb and resource: count keys in a JSON object, and adds that values are discarded. This makes the core intent clear, though it does not explicitly differentiate itself 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 choose this tool instead of validate-json or other sibling tools, and no exclusions or conditions are mentioned. Usage is only implied by the phrase 'Count keys', which is insufficient.

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