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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent mutation. The description adds useful context that it only marks a document as sent rather than performing delivery, but it does not explain repeat-call behavior, permissions, reversibility, or what happens if the document is already marked sent.

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?

The description is a single efficient sentence with the action and the usage condition front-loaded. Every part contributes information and there is no filler.

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 one-parameter mutation with annotations covering safety traits, the description supplies the essential usage context and clarifies that no actual sending occurs. Some edge-case behavior is unstated, but the core definition is complete enough to invoke correctly.

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% and the single "id" parameter is already documented as "Beleg-ID". The description adds no further parameter semantics beyond what the schema provides, which is acceptable for this simple case.

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 states a specific verb and resource ("ausgestellten Beleg als versendet markieren") and clarifies that the document was sent by another route. It is clear what the tool does, though it does not explicitly name the sibling send_document as the contrasting operation.

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?

It gives a clear condition for use: the issued document went to the customer via another channel such as personal email or post. It implies this is not the tool for sending from the system, but it does not explicitly name send_document as the alternative.

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