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

The description mentions that values are discarded, which is a behavioral detail, but it does not explain how the other parameters are handled or whether any side effects occur. The lack of annotations leaves much unspecified.

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 extremely concise, consisting of two short sentences, with no unnecessary words. It directly states the core function and a key behavioral note.

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 nine parameters and no output schema, the description is highly incomplete. It does not explain how to supply the JSON, what the output format is, or how the parameters interact, making it insufficient 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?

The tool description adds no information about the parameters; it does not clarify which parameter is the JSON input or how the others relate to counting keys. The schema already provides per-parameter descriptions, but they do not align with the tool's stated 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 clearly states the action ('Count keys in a JSON object') and a key detail ('Values discarded'), but it does not specify which of the nine parameters represents the JSON object, so the purpose is somewhat muddled by 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?

No guidance is provided on when to use this tool versus any alternatives. The description gives no context for selecting it over the many sibling tools.

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