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

Annotations already declare readOnly, idempotent, open-world, and non-destructive, so the safety profile is covered. The description adds genuinely useful operational context: the upstream provider (Open-Meteo) and that no API key is required. It says nothing about units, timezone of the forecast, or partial-failure behavior for out-of-range coordinates.

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?

A single front-loaded sentence with zero filler; the provider and key note are parenthetical and do not bury the core statement of what the tool returns.

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 three-parameter read tool with a full output schema and complete annotation coverage, the description supplies what the structured fields cannot (data source, no auth). Only minor gaps remain around units and forecast timezone.

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%, with bounds and WGS84 noted per parameter, so the schema does the heavy lifting. The description adds no meaning beyond it, such as what 'forecast_days' returns on day 1 or the timezone the daily forecast is expressed in; 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 the concrete resource returned (current weather plus a daily forecast) and the spatial scope ('for a point'), which cleanly distinguishes it from siblings like get_air_quality, sun_times, or terrain_horizon. It lacks an explicit verb but the retrieval semantics are unambiguous.

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 can infer this is the tool for point weather, but the description names no alternatives (e.g. air quality or sun times) or conditions under which to prefer them. It does note 'no key needed', which removes a setup concern but is not usage guidance.

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