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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds the useful detail that proximity results are distance-sorted and that ids feed estimate/get_data. It says nothing about default limit (50), the 300 km default radius, or whether filters are ANDed, which are the remaining behavioral unknowns.

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 dense sentences that front-load the resource and its fields before listing selection modes. No filler, though the em-dash clause packing four modes into one line is slightly harder to parse than a short list would be.

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?

An output schema exists, so return values need no explanation, and annotations cover safety. However, for an 11-parameter tool with 36% schema coverage, the description should address the limit/radius defaults and whether the filter families are mutually exclusive or combined, which it does not.

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 only 36%, so the description carries extra burden. It does map the search modes to the near_*/lat-lon/text/country parameter families, but leaves limit, radius_km defaults and filter-combination semantics unexplained, so it only partially compensates for the low coverage.

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 resource concretely ('the stations that carry a variable') and enumerates the returned fields (id, name, position, sampling height, country, ecosystem), so an agent knows exactly what comes back. It also clarifies the downstream role of the returned ids. No sibling does the same thing, so differentiation is implicit rather than stated.

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?

Names the four selection modes (near a point sorted by distance, in a box, by name, by country) and explains that the returned ids are the `station=` input for estimate/get_data, which gives a clear workflow context. It stops short of stating when to prefer one mode over another or how modes combine.

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