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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered elsewhere. The description adds the formula provenance and names the return field, which is modest but real context beyond the annotations without contradicting them.

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?

Two tight sentences with the operation and formula front-loaded, followed by a compact 'Returns:' clause. The list_bundles pointer is the weakest element and skews promotional rather than operational, costing a point.

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?

Output schema exists, so the description is not obligated to explain return values further, and param constraints live in the schema. For a two-parameter pure calculator with full annotation coverage, only the missing distinction from heat_index keeps this from being complete.

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 both parameters are already documented in the schema, including the 10C ceiling on temperature_c. The description adds no units, ranges, or edge-case behavior (e.g. wind chill undefined above 10C) beyond what the structured schema supplies, making the baseline 3 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?

States a specific verb and resource ('Calculate the perceived wind chill temperature') and even names the formula variant (Environment Canada), which is meaningful for a tool whose sibling calculate_heat_index covers an adjacent concept. It does not explicitly say how it differs from heat_index or the generic temperature converters, so it stops short of full sibling differentiation.

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, when-not-to-use, or alternative tool is named. The only routing hint ('See list_bundles for related astronomie-nature calculators') is a bundle cross-sell, not guidance on selecting this tool over calculate_heat_index or convert_temperature.

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