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

Annotations already establish the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's remaining burden is light. It adds the shape of the result, but since an output schema exists that information is largely duplicative rather than new behavioral context.

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 short sentences, purpose front-loaded before the routing pointer. Enumerating the return fields consumes most of the length and is redundant given the output schema, so it is efficient but not maximally tight.

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 single-parameter calculator with full schema coverage, complete annotations, and an output schema, the description supplies everything an agent needs to invoke it correctly. Nothing critical is missing; the return-field list is surplus rather than a gap.

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?

Only one parameter (altitude_m) with 100% schema coverage including description and 0-8850 bounds, so the schema carries the semantics. The description adds no unit, range, or interpretation detail beyond what the schema already states; 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?

Specific verb+resource: 'Assess altitude sickness risk and recommend acclimatization schedule.' This is clearly distinguishable from the hundreds of unrelated calculate_* siblings, and no other sibling covers altitude sickness.

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?

Usage is only implied: an agent with an altitude value infers it should use this tool. There is no explicit when-to-use/when-not statement, and the only routing hint ('See list_bundles for related voyage calculators') points to a discovery tool rather than naming an alternative calculator.

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