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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable behavioral context: output rows are grouped per VAT-rate group, expense accounts are selected automatically based on SKR, and the user should verify account mappings before import. There is no contradiction with the annotations.

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 dense sentences with no filler. The output format is front-loaded, the key transformation rule is stated, and the verification caveat is a practical addition that 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?

With an output schema present, full parameter-schema coverage, and annotations covering safety, the description provides enough context to understand the tool's behavior and constraints. The only notable gap is explicit sibling differentiation, but it does not prevent correct invocation.

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 input schema already documents all four parameters with 100% coverage, so the baseline is 3. The description adds slight semantic value by explaining that SKR drives automatic expense-account mapping, but it does not meaningfully elaborate on path, file_base64, or creditor_account beyond 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 title and description state a specific action (exporting an invoice), a precise target format (DATEV Buchungsstapel EXTF 700), and the transformation behavior (one booking row per VAT-rate group, automatic expense accounts by SKR). This clearly distinguishes it from sibling tools like invoice_to_csv and invoice_to_html.

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 description implies the use case — producing DATEV accounting text for an incoming invoice — and includes a tax-advisor verification caveat, but it never explicitly states when to prefer this tool over invoice_to_csv or invoice_to_html, nor when not to use it. The routing between siblings is left to inference.

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