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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description's return-shape listing is largely redundant with the existing output schema and it discloses no edge-case behavior (e.g., validity ranges for heat index). With annotations carrying the safety burden, a 3 is appropriate.

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?

Three short sentences, front-loaded with the core purpose. The explicit Returns block is somewhat redundant given a formal output schema exists, but overall it is tight and earns most of its space.

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 simple 2-parameter, fully-documented tool with an output schema and full annotations, the description covers purpose, inputs, and returns sufficiently. The bundle cross-reference adds useful context; only minor gaps (physical validity constraints) remain.

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 (humidity 0-100%, temperature in C). The description names the inputs but adds no units, ranges, or format detail beyond what the schema provides, so the baseline 3 applies.

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 (Calculate) and resource (apparent temperature / heat index) plus the two inputs, making it clearly distinguishable from siblings like calculate_wind_chill or calculate_dew_point. An agent can identify the tool's function without opening 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?

The description implies its use (given temperature and humidity) and offers a cross-reference to list_bundles for related calculators, but it gives no explicit when-to-use vs. when-not guidance nor names the closest alternative tools. Adequate but with a clear gap.

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