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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value: newest-first ordering, the fields returned in each row, the special semantics of the overdue filter, and an authentication prerequisite (Cotlet API key with access to this app).

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?

Four tight sentences with no filler: purpose and document types first, then what is returned and ordering, then filter semantics, then downstream ID usage and auth. Every clause carries information an agent needs.

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 no output schema, the description usefully enumerates the returned fields and ordering, and all six optional parameters are documented in the schema (including the pagination cursor). Only minor pagination/limit behavior is left to the schema, so the definition is essentially complete for this read-only list tool.

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%, so the baseline is 3. The description goes slightly beyond the schema by explaining that 'overdue' is not a stored state but returns open invoices whose due date has passed, which changes how an agent should interpret the status enum and interact with combining filters.

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 concrete verb+resource ('Lists sales documents from the Belege list') and enumerates the document types covered (invoices, quotes, order confirmations, delivery notes). It also distinguishes itself from its siblings by pointing at get_document, finalize_document and send_document as the follow-up tools, so an agent can tell it apart without opening a 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?

Gives clear operating context: filter by type and status, overdue returns open invoices past their due date, and the returned IDs feed get/finalize/send_document. It does not state when NOT to use it or name an alternative list/search sibling, so it stops short of an explicit routing rule.

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