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

Annotations already cover read-only/idempotent/non-destructive, and the description adds real value beyond them: confidence caveats ('model water visibility, low confidence'), 'curated seasons are drafts pending local review', source provenance per field, and that the call is free. Return-shape detail is thinner but an output schema exists.

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?

Front-loaded with the core purpose and the input contract, then the field inventory. The long return-field list is partly redundant given an output schema exists, but it is dense and free of filler.

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 annotations, a 100%-covered schema, and an output schema, the description covers what remains: the trip-planning horizon, confidence caveats, provenance, and cost. Only cross-tool routing guidance is missing.

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 all six parameters are already documented. The description only restates the input forms ('area id, a spot id, or lat+lon') without clarifying precedence when several are supplied, so it stays at the baseline.

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: what a place is usually like in a given month, with the full field inventory named. The 'usually / months ahead' framing implicitly separates it from the current-conditions sibling, but no sibling is named explicitly.

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?

'For trip planning months ahead' establishes the use context, and 'Pass an area id, a spot id, or lat+lon, and optionally a month range' tells the agent how to invoke it. It does not state when to prefer best_months, best_day, or get_conditions instead.

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