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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read-only nature is covered. The description adds the scope 'des Partners' and the filtering dimensions, but it does not disclose pagination behavior, ordering, or return format; with the annotations doing the heavy lifting on safety, this is adequate but not rich.

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 compact bilingual sentence pair, front-loaded with the core action and containing no filler. The EN repetition is mildly redundant but serves clarity for multilingual agents, so it remains appropriately concise.

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 7 parameters, no output schema, and a closely related sibling (letter_search), the description is under-specified. It omits pagination/limit/offset semantics, return shape, and any guidance for choosing between letter_list and letter_search, leaving a substantial gap for 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?

Schema description coverage is 0%, so the description must compensate. It adds meaning by mapping filter concepts to parameters: recipient name (recipientNameContains), subject (subjectContains), status (statusFilter), and time (since). However, it does not explain limit, offset, or reasoning, which remain ambiguous despite the low schema coverage.

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 clearly states a specific action ('Listet'/'Lists') and a specific resource ('Briefe des Partners'/'partner's letters'), and it names the main filter dimensions (recipient name, subject, status, time). It does not explicitly distinguish itself from the sibling tool letter_search, which likely overlaps in function, so it is clear but not fully differentiated.

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 explains what the tool does and mentions optional filters, but it gives no guidance on when to choose letter_list over letter_search or letter_get. No exclusion criteria or alternative routing is provided, leaving the agent to infer usage from the name alone.

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