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

Beyond the readOnlyHint=false annotation, the description discloses concrete behavioral outcomes: amount and date defaults, full payment marks the invoice paid, and overpayment is rejected in favor of a credit note. This gives the agent a clear picture of the mutation's side effects.

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 focused sentences with no filler; the core action, defaults, and edge case are front-loaded in a logical order. Every sentence earns its place.

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?

The description plus fully covered schema is nearly sufficient for a correct call. It lacks an explicit mention of the account prerequisite (present only in the title) and does not describe the success/error response, leaving minor uncertainty for an agent.

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?

The schema already documents all four parameters at 100% coverage, so the baseline is 3. The description adds value by clarifying betrag behavior beyond the schema (full coverage marks paid, overpayment rejected), but it mostly restates defaults already present in the schema.

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 names a specific verb and resource ('Verbucht einen Geldeingang auf eine Rechnung') and is clearly distinct from siblings like rechnung_erstellen or rechnungen_suchen. The scope is unambiguous.

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 context for use is clear: record an incoming payment against an invoice, with defaults and edge behavior stated. It explicitly excludes overpayments and directs the user to create a credit note instead, though it does not name an alternative tool and says little about when not to use it beyond that case.

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