Température de la mer et houle à La Réunion

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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the description's added value is the data provenance and shape: satellite-measured values with date and distance, model forecasts with height/period/direction, returned in two separate blocks. That output structure is useful context with no output schema present. It doesn't mention coverage limits or how stale measurements can be.

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 resource and the measured-vs-forecast distinction, and each clause contributes either trigger phrasing or output structure. The wholesale French/English duplication inflates length, though it may be justified for this French-language service.

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-optional-parameter read tool with no output schema, the description supplies the essential missing pieces: what each of the two result blocks contains and the 4-day forecast horizon. Remaining gaps (measurement staleness, unit of temperature) are minor.

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% and the lieu parameter is documented in detail (commune, beach, quarter, cirque, summit, lat/lon, empty = whole island). The description only restates 'près d'une plage ou d'un lieu côtier' and adds no syntax or format detail beyond the schema, 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?

The description names two distinct resources with specific verbs: measured sea temperature (satellite) and forecast waves (model, 4 days), and gives concrete example phrasings. It separates 'measured' from 'forecast' clearly, which is genuinely differentiating, but it never names the close siblings (maree, prevision_meteo, meteo_actuelle) an agent might confuse it with.

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?

Example user utterances (« la mer est à combien à Saint-Leu ? », « ça surfe à Saint-Pierre demain ? ») make the intended trigger conditions clear, including the 4-day forecast horizon. There are no explicit exclusions or named alternatives for adjacent tools, so it stops short of a 5.

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