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

Annotations already declare a safe read-only, closed-world, non-destructive operation, yet the description adds meaningful behavior: the catalogue grows with each curated/passed-review design, and the cost profile changes sharply depending on whether presetId triggers PNG rendering. The cost tradeoff is genuinely useful context annotations cannot express, though rate limits or result-size bounds are unmentioned.

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?

Content is front-loaded and well ordered, but the German and English versions are full duplicates, doubling the length without adding information. Every sentence is useful once, but the payload is roughly twice the necessary size.

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 read-only list tool with no output schema, the description adequately covers modes, cost and content, but leaves the preview mechanics vague: what 'pages' controls (limit 2), what resolution thumb vs full means, and whether reasoning is required for audit are all unexplained.

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 25%, and the description covers only presetId (whose semantics are already in the schema description). The 'pages' cap (max 2), the 'resolution' thumb/full enum, and 'reasoning' are left undocumented in both places, so the low-coverage gap is only partially compensated.

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?

States a specific verb and resource: returns owner-approved native-v2 letterheads as safe starting points, and enumerates the document classes they suit. This is clearly distinguishable from siblings like letter_design_list (user designs) and letterhead_list without opening either schema.

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 explicitly explains the two operating modes: omit presetId for a cheap text-only list, supply presetId to render exactly one composer preview with an inline PNG. It gives clear context for choosing between the modes but never names an alternative sibling tool or states when this list should be preferred over letter_design_list.

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