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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description usefully reinforces this with 'Kein Auftrag, keine Kosten', confirming no side effects. It still says nothing about what the response contains (total only or itemized, currency), which matters since there is no output schema.

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?

Two short sentences, no filler. The core purpose with its price components is front-loaded, and the no-side-effects caveat follows immediately.

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?

Low-complexity read-only calculator with fully documented parameters and annotations covering safety, so the description is nearly complete. The one gap is the return shape — no output schema exists and the description never says whether the agent gets a single total or a breakdown per component.

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 each parameter carries a rich in-schema description including page-to-letter-class mapping and Einschreiben surcharges. The description merely names the same three inputs (Seitenzahl, Einschreiben-Wahl, Zielland) and adds no semantics beyond the schema, so the baseline 3 applies.

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 (berechnet) and resource (Endpreis eines Briefes) and enumerates the price components (Druck, Kuvert, Porto) plus the three driving inputs. It does not name the sibling send_letter explicitly, but 'Kein Auftrag, keine Kosten' makes the boundary clear enough that an agent won't confuse it with an ordering tool.

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?

'Kein Auftrag, keine Kosten' implies preview-only usage, which hints that this is the tool to call before committing to send_letter. However, it never explicitly says when to use it vs. send_letter or whether a quote is required before ordering, so the routing guidance stays implicit.

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