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

Annotations already declare readOnly=true / destructive=false, so the safety profile is covered. The description adds real value beyond that: results are ordered newest first, amounts are signed (in positive, out negative), and it names the auth requirement (Cotlet API key with app access).

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?

Two of the sentences largely restate the same field list (date, amount, counterparty, booked status vs. amount, payer/payee, purpose, booked), which is redundant. Useful details (ordering, signed amounts, auth) are present but buried behind the repetition.

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 and full schema coverage, the description is nearly complete: it names the returned fields, ordering, amount sign convention, filter semantics and auth. It stops short of explaining cursor-based paging, which would help an agent iterate pages correctly.

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 coverage is 100%, so the baseline is 3, but the description goes further by explaining the business meaning of unbooked_only (transactions still needing a receipt or invoice) and the sign convention for amounts, which the schema does not state.

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 ('Transactions of one payment account') and enumerates the returned fields, so the agent knows exactly what this retrieves. It does not explicitly differentiate from the sevdesk siblings (list_vouchers, list_payment_accounts), but the resource is distinct enough that confusion is unlikely.

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?

Provides one conditional usage cue ('Set unbooked_only to see the ones that still need a receipt or invoice'), which is genuinely useful. However there is no when-to-use-this vs. alternatives guidance, no statement of prerequisites for calling it, and no note on pagination workflow.

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