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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful context by stating that the response includes the full design JSON and that designs cover all mail categories, but it does not disclose pagination, ordering, or result structure in more detail. No contradiction with 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?

The description is front-loaded with the main purpose and is reasonably compact, but it duplicates the full content in German and English, which adds length without new information. The mail-category sentence is contextually useful but not essential.

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 simple list tool with two optional parameters, the description gives the core purpose and result content. However, with no output schema and one parameter left entirely unexplained, an agent still lacks complete information about the return value and the intended use of the 'reasoning' argument.

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 only 50%: the 'reasoning' parameter is undocumented in both the schema and the tool description. The 'includeArchived' parameter is described in the schema, but the description itself adds no parameter-level meaning and does not compensate for the undocumented reasoning field.

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 identifies the specific resource ('Briefpapiere/Briefdesigns') and the action ('Listet'), and adds that it returns the full design JSON. It is clear and self-contained, though it does not explicitly distinguish itself from closely related siblings like letter_design_list_presets or letterhead_list.

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 usage: designs are referenced by name or ID when sending mail, so an agent can infer that this tool is for looking up saved designs. However, there is no explicit when-to-use statement, no exclusions, and no comparison to the closely related siblings.

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