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

There are no annotations, so the description carries the full burden of behavioral disclosure. 'Number discarded' is cryptic and does not explain whether the tool performs checks, has side effects, requires permissions, or returns anything. The schema's 'discarded after the check' notes appear only in the input schema, not in the description itself.

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 very short, but it is under-specified rather than appropriately concise. Its single phrase does not earn its place because it fails to explain the tool's actual inputs or behavior.

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 nine parameters, no required fields, no annotations, and no output schema, the five-word description is drastically incomplete. It gives an agent almost nothing needed to invoke the tool correctly or understand its purpose.

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 input schema already documents all nine parameters in detail. The description adds no parameter meaning beyond the schema, so the baseline of 3 is appropriate.

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 says 'Furlongs to meters, number discarded', but the tool exposes nine string parameters (ref, url, city, feed, host, json, path, zone, query) with no furlong or numeric input. This is misleading: an agent would expect a unit-conversion tool, yet the schema implies shape-checking utilities. It neither distinguishes this tool from siblings like calc-eval nor accurately names the resource handled.

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 when-to-use guidance, no exclusions, and no alternatives are mentioned. The description gives no indication of when this tool should be selected over siblings such as calc-eval, timezone, validate-json, or normalize-url.

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