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

Annotations already declare readOnly, openWorld, and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior: the register is refreshed at most hourly (freshness/rate), it returns name suggestions on mismatch, and it explicitly is not an official warning. It omits return format/pagination detail, keeping it below 5.

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 front-loaded with what is returned, then constraints, then examples, with little waste. The trailing instruction about citing source and license is slightly appended but operational and justified.

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 carries the return burden and does so by enumerating the returned fields. Freshness limits, the mismatch fallback, and the non-warning disclaimer give an agent enough to invoke and interpret it, though the exact response shape is only summarized.

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 100% and already documents the format (name without article, e.g. "Enns"). The description adds meaning beyond the schema by requiring the name to match the register and disclosing that suggestions are returned on deviation, which an agent needs to handle input correctly.

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 states a specific verb and resource: retrieving all current measurement stations (with value, unit, timestamp, location, trend) for an Austrian water body. It clearly distinguishes the scope from a spatially-filtered sibling, but never names pegel_in_der_naehe or lage_am_ort explicitly, so the sibling boundary is only implied.

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?

Concrete trigger examples ("Wie ist die Lage an der Donau?", "Welche Messstellen gibt es an der Mur?") make the intended use clear, and the name-matching rule with fallback suggestions sets expectations. It still does not state when to prefer this over pegel_in_der_naehe or hochwasserlage, so no explicit when-not guidance.

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