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

Annotations already declare the safe-read profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds real context beyond them: the returned fields, the ~1,400-station coverage including closed stations, and the distance value that appears only for lat/lon searches.

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?

Four short sentences, front-loaded with the core purpose, then return fields, then sibling routing, then coverage. No filler; every sentence carries distinct information.

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?

There is no output schema, yet the description enumerates the return fields and notes the conditional distance field, plus the station universe and source. An agent has everything needed to call it and interpret results.

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%, so all five parameters are already documented in the schema (including lat/lon pairing, substring/umlaut matching, and limit defaults). The description only restates the two search modes, adding no syntax beyond what the schema provides — baseline 3.

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 a specific verb (Find) and resource (DWD climate stations) with two clear search modes: by name or nearest to a coordinate. It distinguishes itself from siblings by explicitly naming dwd_daily and dwd_latest as the downstream consumers of the returned station_id.

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?

"Use the station_id with dwd_daily or dwd_latest" gives explicit routing to the correct follow-up tools, and the two search modes are spelled out. It lacks any when-not guidance (e.g. when not to use this vs. another lookup tool), so it falls short of a full 5.

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