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

Annotations already flag destructiveHint=true and idempotentHint=false, so the safety profile is covered. The description adds genuinely new behavioral facts: cancellation immediately spawns a numbered Stornorechnung, is irreversible, and leaves already-received payments with the customer — a real financial consequence not encoded anywhere else.

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 short clauses, front-loaded with the action, then the side effect, then the irreversibility warning. No filler; every sentence carries distinct information.

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 destructive two-parameter mutation with no output schema, the description covers the key unknowns: side effect, reversibility, and payment implications. Only the parameter-level meaning and any permission requirements are left unaddressed.

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 only 50%: 'id' is described tersely as 'Beleg-ID' and 'reason' has no description at all. The description mentions neither parameter, so it does not compensate for the gap — an agent gets no help on what 'reason' is used for or whether 'id' refers to the invoice or another document type.

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?

Names a specific verb and resource ('Ausgestellte Rechnung vollständig stornieren') and immediately explains the mechanism: a Stornorechnung with its own number is issued. This is more specific than the title alone, though it does not explicitly contrast with the sibling create_credit_note, which is the closest alternative.

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?

'Ausgestellte Rechnung' implicitly scopes usage to already-issued invoices (not drafts, cf. delete_draft), and 'Nicht rückgängig zu machen' signals caution. However, there is no explicit guidance on when to cancel vs. issue a credit note via create_credit_note — the most relevant routing decision an agent faces here.

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