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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: data refreshes at most hourly, this is explicitly NOT an official warning (Keine amtliche Warnung), and the response carries the data provider's source note and CC BY 4.0 license link.

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?

Front-loaded with the returned data, then matching rule, freshness, warning disclaimer, examples and license note. Every element is useful, though the example-question list and license sentence make it longer than strictly necessary for invocation.

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 compensates by enumerating the returned fields, stating freshness limits and the licensing/footer behavior. Combined with a 1-parameter schema it is close to complete; only the shape of the mismatch-suggestion response is left vague.

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 the single parameter is already documented (name without article, e.g. 'Donau'). The description goes further by defining the matching rule against the Pegelbestand and the fallback suggestion behavior on mismatch, which the schema does not express.

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+resource: returns all current gauging stations (Pegelmessstellen) on an Austrian water body, listing exactly which fields come back (value, unit, measurement time, location, tendency). The 'an einem Gewässer' scope contrasts cleanly with the sibling pegel_in_der_naehe (by location), so an agent can pick between them without opening a schema.

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?

Gives explicit invocation conditions: the water-body name must match the official Pegelbestand, and mismatches return suggestions, plus three example questions that model the expected input. It stops short of naming alternatives (e.g. hochwasserlage for warnings or pegel_in_der_naehe for proximity), so routing guidance is implied rather than complete.

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