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. It does reveal a useful trait: values are discarded rather than returned or retained. However, it omits whether counting is top-level only or recursive, what input is expected, and what the return value looks like, so transparency is partial.

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 two tight clauses with no filler, front-loading the core action ('Count keys') and adding one behavioral detail ('Values discarded'). Every word contributes to the tool's meaning.

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 nine optional schema parameters, no output schema, and no annotations, this one-sentence description is too thin. It does not specify which parameter holds the JSON input, how nested or top-level keys are counted, what the output format is, or how this relates to sibling validation/shape tools.

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 the baseline of 3 applies even though the description adds no parameter-specific meaning. The schema properties have descriptions, but they are oddly framed as validation/shape-check inputs rather than counting inputs, leaving ambiguity about how to supply the JSON object to count.

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 clearly states the verb and resource: count keys in a JSON object, and adds that values are discarded. It is specific enough to distinguish this from validation-oriented siblings like validate-json, though it does not explicitly call out any sibling or clarify how the JSON object is passed in the schema.

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?

There is no guidance on when to use this tool versus alternatives such as validate-json or other shape-checking siblings. The intended use is only implied by the name and the one-line description, with no exclusions, prerequisites, or alternative routing.

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