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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose that values are discarded, which is useful, but it omits the return format, behavior on invalid JSON, side effects, and whether any values are persisted or accessed.

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 operation is front-loaded and the important caveat 'Values discarded' follows immediately. The structure is exemplary, even though the content is thin.

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?

With 9 optional parameters, no required fields, no annotations, and no output schema, the agent cannot determine which arguments are relevant or what the return value will be. The sparse description is inadequate for confident invocation beyond guessing at the `json` parameter.

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 is 3. The description plausibly maps to the `json` parameter, the only JSON-related field, but it never explicitly says to populate that parameter, and the schema description for `json` focuses on validation, not counting keys, creating ambiguity across the 9 optional parameters.

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 specific verb and resource: count keys in a JSON object. The additional phrase 'Values discarded' clarifies a key behavioral qualifier and distinguishes it from validation or shape-checking tools. It is clear about the core operation, though it does not name which input parameter carries the JSON 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?

There is no guidance about when to use this tool versus siblings like validate-json, domain-shape, or jira-key-shape. The description implies counting keys, but it never states explicit conditions for use or mentions alternatives.

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