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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial behavior beyond them: the upstream source (MET Norway Locationforecast 2.0), that speeds are 10-minute means at 10 m height, that gusts appear only where MET Norway supplies them, and a 1-credit cost. These caveats materially affect how an agent should interpret and budget the call.

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 what the tool returns before drifting into use-case examples, prerequisites, source and cost. Dense and mostly waste-free, though the activity list ('cycling, sailing, drone flying, kite flying or securing garden furniture') is slightly padded relative to the rest.

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 3-parameter read-only tool with no output schema, the description covers units, measurement basis, data source, coverage window, caveats, cost and the coordinate prerequisite. An agent has everything needed to call it correctly and interpret the results without further clarification.

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 coverage is 100%, so a baseline of 3 applies, but the description adds real meaning: coordinates refer to 'any point' globally, and the note about fetching coordinates from geocode/postcode_lookup explains why lat/lon accept strings and heads off passing a place name directly. The hours window meaning is mostly duplicated from the schema.

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 ('Hourly wind forecast for the next 1-48 hours at any point') and enumerates exactly what is returned: speed in four units, compass direction, and Beaufort force with name. That scope cleanly separates it from sibling forecast tools such as weather, marine_forecast, cloud_cover_forecast and rain_forecast_next_hours without requiring the agent to open any 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?

Gives concrete use contexts (cycling, sailing, drone/kite flying, securing garden furniture) and an explicit prerequisite chain: for a UK place name or postcode, obtain coordinates from geocode or postcode_lookup first. It does not explicitly say when to prefer the general 'weather' or 'marine_forecast' sibling instead, so the exclusion half of the guidance is missing.

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