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

With no annotations and only the phrase 'Values discarded', the description does not disclose return format, errors, side effects, or any observable behavior beyond counting.

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 a single, front-loaded sentence with no fluff, though it is so terse that it leaves important operational details unstated.

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?

Given there is no output schema or required parameter, the description should explain what input shape is expected and what the tool returns; it does neither, making the tool effectively unusable from the description alone.

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 the schema has 100% description coverage, the parameter descriptions are contradictory to the stated purpose—most are described as 'discarded' or tied to unrelated checks, so they do not clarify how to provide the JSON object whose keys are counted.

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 object ('Count keys in a JSON object'), but the input schema contains nine unrelated optional string parameters, so it is unclear what actual input the tool consumes.

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 about when to use this tool versus alternatives like validate-json or calc-eval, and the description does not mention any selection criteria.

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