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

With no annotations, the description carries the full behavioral disclosure burden. It does disclose a non-obvious behavior: 'Values discarded.' But it does not say whether the count is top-level only, how invalid JSON is handled, whether input is validated, or what the return value looks like.

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 concise and front-loaded, with no wasted words. It loses a point because its brevity omits any pointer to the confusing parameter set, which the schema does not resolve.

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 9 optional parameters, no output schema, and no annotations, this description is not complete enough. It omits how to pass the JSON object, what the result format is, whether nested keys count, and how errors or unexpected input are handled.

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?

Although schema coverage is 100%, the schema does not clearly map to the description. Parameters like url, city, feed, and path are unrelated to counting JSON keys, and the 'json' parameter is described as 'JSON text to validate; discarded after the check' rather than as the object to count. The description adds no parameter mapping, so an agent cannot confidently invoke the tool.

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 clear verb and resource: 'Count keys in a JSON object.' It also clarifies that values are discarded, which distinguishes it from validation-style siblings like validate-json. However, it does not explain how the tool relates to its 'memory' name or how the JSON object is supplied.

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 description gives no explicit guidance on when to use this tool versus alternatives such as validate-json, domain-shape, or search-query-len. The phrase 'Values discarded' weakly implies key-count-only use, but there is no when-to-use or when-not-to-use statement.

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