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

With no annotations present, the description must carry the behavioral burden. It discloses that values are discarded, which is meaningful, but it does not explain whether counting is top-level or recursive, whether it returns a plain number, or whether the input should be passed through the json parameter.

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 short sentences with no filler. The main action is front-loaded, and the discarded-values note is efficiently placed second.

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 input schema is large and confusing, with nine optional parameters drawn from unrelated domains, and there is no output schema. The description does not state the return format, the top-level-versus-recursive counting behavior, or which parameter to supply, so an agent lacks enough context to invoke 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?

Schema coverage is 100%, so the high-coverage baseline of 3 applies. The description adds no parameter-level guidance and does not clarify which of the many optional parameters should receive the JSON object, but the schema descriptions already define each parameter individually.

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. The second sentence clarifies a key semantic, values are discarded. It does not explicitly differentiate this from sibling tools such as validate-json, so it misses the top score.

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 intended use is implied by the description: invoke it when a key-count of a JSON object is needed. However, it provides no explicit guidance about when not to use it or which sibling tools are alternatives, so the agent must infer the boundary.

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