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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false; the description adds substantial context beyond that: the regional data-coverage limitation, the semantics of an empty answer (all-clear only if `coverage` says so, otherwise "du es nicht weißt"), truncation semantics (`limit` caps, `truncated` + `total` signals), and anti-fabrication rules (never attribute an unplaced report to a line/place). This is exactly the context annotations alone cannot convey.

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?

The description is long but densely structured with bold leads ("Datenlage — wichtig", "Keine Pflicht-Args", "Format", "Anleitung", "Anti-Fab"), and the most safety-critical caveat (data coverage) is front-loaded right after the purpose. Every sentence earns its place; the length is long but justified by the open-world and anti-fabrication stakes for a 6-param, 0-required tool.

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?

For a tool with openWorldHint=true, no output schema, and heavy inference risk, the description is complete: it covers purpose, data limits, filter semantics, output format (TOON, not JSON), a concrete pointer to the six coverage values via `get_usage_guide`, and truncation indicators. The one deferral to the usage guide is a legitimate division of labor rather than a gap.

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 the schema itself already documents all six parameters richly (e.g., `area` "never suppresses a report`). The description adds meaning beyond the schema by spelling out the AND-combination of `line` and `stop`, the `area`→`coverage` relationship, and the directive to pass only user-named filters — genuinely additive, just leaving the baseline 3 one notch higher.

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 opens with a specific verb+resource: "Aktuelle Störungen, Baustellen und Liniensperrungen im ÖPNV" — a clear, specific queryable scope. It further distinguishes itself from siblings by stating it is the answer source for disruption queries "nicht das Allgemeinwissen" and by explicitly separating disruptions from connections/departures, which are "deutschlandweit" covered.

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?

The description states explicitly when to use it ("Für ‚gibt es Störungen"), gives an exclusion boundary (no data basis "außerhalb" Niedersachsen/Bremen/Hamburg), and routes alternatives ("Verbindungen und Abfahrten sind davon nicht betroffen"). It even specifies response interpretation rules conditioned on the `coverage` field, leaving nothing to inference.

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