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

No annotations are provided, so the description carries the full disclosure burden. "Number discarded" hints at a discard/no-retention behavior, but it refers to a parameter that does not exist in the schema, and it says nothing about the discard semantics of the nine real inputs (which the schema descriptions handle instead).

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?

It is short, but the brevity comes from being a cryptic fragment rather than from disciplined editing. It is not front-loaded with any actionable information an agent could use.

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 optional parameters, no annotations, and no output schema, the description should explain scope and effect. Instead it describes an unrelated unit conversion, leaving the tool's actual behavior and inputs entirely unexplained.

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%, which normally sets a baseline of 3, but the description contributes no parameter meaning and instead implies a numeric "number" input absent from the schema, actively muddling the parameter model rather than supplementing it.

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 names a conversion ("Nits to cd/m2") and a disposition ("number discarded"), but none of the nine actual parameters (ref, url, city, feed, host, json, path, zone, query) relates to nits, luminance, or a numeric input. An agent reading only this line cannot tell what the tool actually operates on, and the stated resource does not match 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?

There is no when-to-use statement, no condition, and no reference to any sibling tool despite many adjacent validators (domain-shape, file-path-ok, validate-json, iana-zones). Nothing routes the agent toward or away from this tool.

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