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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so safety is covered structurally. The description's one useful addition is the "authenticated" cue implying credentials are required, but it says nothing about response shape, units, or failure modes for a non-idempotent, open-world 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?

It is short, but half of it is wasted restating the tool name in router boilerplate, and the remaining clause is vague. Brevity here reflects under-specification rather than disciplined concision.

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, no parameter documentation, and a one-line description, the definition is too thin for a tool with a required identifier. It should at minimum name the resource returned and clarify how station_id is sourced.

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?

There is a single required parameter, station_id, with 0% schema description coverage, and the description never mentions it. The agent gets no hint about accepted identifier forms (e.g., NRFA gauging-station number) or constraints beyond the integer/positive type.

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?

"TerraMCP authenticated router: nrfa_station_info" merely restates the tool name, and the only functional claim is "Returns normalised SI data and source provenance." It never says it returns National River Flow Archive station metadata, and it gives no basis for choosing this over nrfa_get_timeseries or the flood/rainfall station siblings.

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?

There is no when-to-use, no when-not-to-use, and no mention of any alternative. With siblings like nrfa_get_timeseries and flood_find_stations sharing the NFRA/station domain, the agent is given nothing to route by.

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