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

Annotations already declare destructiveHint=true and idempotentHint=true, but the description adds genuinely non-obvious behavioural context: the change propagates to all future invoices/offers and to not-yet-issued drafts, while issued documents retain their original values. It also lists the immutable field set and the refer-to-Meistron fallback, which no annotation conveys.

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?

Four sentences, each carrying distinct information: effect, immutability list, escalation, prerequisite. The scoping constraint is front-loaded, though the first sentence is dense enough that the semicolon-joined clauses take a second read.

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 mutation tool with no output schema, the description covers effect, exclusions and the required pre-read, which is close to everything an agent needs. It does not describe what a successful call returns or how the result should be confirmed, a minor residual 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 description coverage is 100%, so feld, wert and idempotency_key are already fully documented in the schema (including the idempotency-key handshake). The description only reinforces that valid field names come from einstellungen_ansehen, which the schema already states, 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 (ändert) and resource (Firmen- oder Rechnungsvorgabe) and immediately scopes the blast radius to all future invoices and offers. It is trivially distinguishable from its read-only sibling einstellungen_ansehen, which it names.

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 an explicit prerequisite workflow ('Vorher „einstellungen_ansehen" aufrufen, um den heutigen Wert zu kennen') and enumerates the fields that are NOT changeable even with approval, plus the escalation path ('verweist auf Meistron'). An agent knows both when to use it and when to refuse.

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