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

Annotations already establish read-only, idempotent, non-destructive and closed-world behavior, so the description is free to add domain behavior — the >8-hour threshold for one-day trips, the treatment of arrival/departure days, and the deduction of employer-provided meals. That is substantive context beyond the structured fields, though it says nothing about the shape of the result.

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?

Three dense sentences with the core operation front-loaded, then the multi-country rule and the meal deduction. No filler, though the clauses are packed tightly and could be slightly better separated.

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 rules-heavy tax calculation with a rich input schema but no output schema, the description covers the input-side logic well but never indicates what comes back (per-day amounts, total, breakdown) nor the link to the rate-lookup siblings. Adequate, but an agent lacks a picture of the result.

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 schema already documents land, tage, laender, mahlzeiten and stunden_eintaegig. The description restates the laender rule and adds that provided meals are 'gekürzt', which clarifies effect rather than syntax; with the schema doing the heavy lifting, the baseline 3 is appropriate.

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 and resource ('Berechnet den Verpflegungsmehraufwand einer Reise') and enumerates the calculation modes (single-day by hours, multi-day with arrival/departure plus full days). It does not explicitly contrast itself with the sibling pauschalen_* lookup tools, so an agent must infer that this one computes rather than returns raw rates.

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 clear context for the two calculation paths (eintägig vs. mehrtägig) and states the condition under which the 'laender' parameter applies ('Bei Reisen durch mehrere Länder'). It stops short of naming pauschalen_land or pauschalen_alle_laender as the alternative for pure rate lookup, so no explicit exclusion is provided.

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