units.temperature

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

Annotations already declare readOnly/idempotent/closed-world, yet the description still adds real value: an error is raised for inputs below absolute zero, and 5/9 is approximated to 50 significant digits, which matters for precision-sensitive callers. It also defines the return shape (value plus uppercase scale), none of which is in the annotations.

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?

Four tight sentences: scope first, then parameter contract, then error rule, then the precision/exclusion caveat. No filler, and each sentence adds information an agent would otherwise have to guess.

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 an output schema present, the description needn't explain return values, yet it does anyway; combined with the absolute-zero error rule and precision note, a caller has everything needed for correct invocation. The only gap is not pointing to the generic units.convert sibling for non-temperature conversions.

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 0% and there are no enums, so the description carries the full burden — and does: value is a Decimal string, from_scale and to_scale are case-insensitive single letters. This covers all three required parameters with format and validation semantics the bare schema lacks.

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?

States a specific verb and resource (temperature conversion) and enumerates every supported scale (C, F, K, R), so an agent can tell instantly this is the temperature-specific converter rather than the generic units.convert sibling. It also scopes the tool to absolute temperatures, not deltas.

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?

Gives an explicit exclusion: it is for absolute temperature values, not temperature differences (Δ). It does not name a sibling alternative (e.g. units.convert) for other cases, so context is clear but routing advice is not exhaustive.

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