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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so the safety profile is covered. The description adds two pieces of context beyond the annotations: that calls require authentication ('authenticated router') and that results carry normalised SI units plus source provenance. It does not explain the unusual idempotentHint=false for what appears to be a read, nor any rate limits or result caps.

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 with no filler, which is good, but the opening clause 'TerraMCP authenticated router: flood_find_stations' merely restates the tool name and title rather than front-loading the actual function. The routing hint is placed after the boilerplate instead of first.

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 no output schema, the description is the only place return values could be explained, and 'normalised SI data and source provenance' is too vague for a spatial station search (no mention of station list, distances, or metadata fields). Combined with 0% parameter coverage and no guidance on units or pagination via limit, it leaves meaningful gaps for a 5-parameter tool.

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 0% across five parameters, so the description must carry the burden, and it largely does not. It clarifies only the 'parameter' enum (rainfall) and leaves lat, lon, radius_km, and limit entirely unexplained — an agent must infer that radius_km is the search radius and limit caps results.

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 name plus 'flood_find_stations' implies a station lookup, and the description adds that it returns normalised SI data and source provenance, plus a rainfall-specific hint. However it never states the core operation (find flood monitoring stations near a lat/lon within a radius), and the 'authenticated router' framing is boilerplate rather than purpose. Sibling tools like rainfall_stations and nrfa_station_info are named only in passing.

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?

It gives one conditional routing rule: 'Set parameter=rainfall to find rainfall stations, or use rainfall_stations', which is genuinely useful alternative-pointing. But there is no guidance on when to choose this over flood_get_readings, nrfa_station_info, or ea_hydro_series, and no mention of required lat/lon proximity context.

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