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

Annotations are all false, so the description carries the behavioral burden and does disclose meaningful traits: the design is fully validated before storage, checked against postal clear zones (Zustellzonen), and the tool returns a hash of stored source data. This goes beyond the schema. It stops short of stating overwrite/update behavior (what happens when designId is passed or a name is reused), but the disclosed validation and return-value behaviors are genuinely useful.

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 essential purpose and return values are front-loaded in the first sentence, which is good. However, the description is bloated: the full bilingual repetition doubles length, and the enumeration of every mail type (Kuendigung, Rechnung, Mahnung, Angebot, Vertrag, Behoerdenpost) is illustrative filler rather than load-bearing 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 complex tool with a massive two-version nested schema and no output schema, the description covers the core contract: what it saves, where, what it validates, and what it returns. It does not explain update semantics (passing designId to modify an existing design), the purpose of the reasoning parameter, or what happens on validation failure — gaps an agent would benefit from knowing before first 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?

Schema description coverage is 40% (name and brandingOwnershipConfirmed have descriptions in the schema). The tool description mentions schemaVersion 1 or 2 support, which touches design semantics, but it does not explain the undocumented parameters: designId (which doubles as an update handle given the returned designId), reasoning, or the update-vs-create meaning of brandingOwnershipConfirmed. With coverage below 50%, the description needed to compensate more than it does.

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 (saves/speichert), resource (reusable letterhead/Briefdesign), scope (partner profile), and what it returns (designId + source-data hash). It clearly distinguishes itself from siblings like letter_design_delete, letter_design_list, and letter_design_preview, which are different operations on the same resource.

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 when to use the tool — saving a reusable design so it carries all mail types (cancellation, invoice, reminder, etc.) — which gives contextual motivation. However, it does not explicitly state when not to use it or route to alternatives (e.g., letter_design_list_presets for preset-based designs, or letter_design_preview for checking before saving). The recovery hint about searching for letter_design_save is operational, not usage guidance.

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