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

With readOnlyHint/destructiveHint already covering the safety profile, the description adds real behavioral detail: guaranteed oldest-first due-date sorting, the per-row return fields (remaining amount, due date, PDF link), and the auth requirement of a Cotlet API key with app access. It doesn't mention pagination behavior despite the cursor param, which caps it below 5.

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?

Front-loads the resource definition before drilling into filters, return shape, sorting, and auth. Six sentences are slightly more than strictly necessary (the opening two overlap somewhat), but each carries distinct 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?

No output schema exists, so the description correctly compensates by describing row contents and sort order. Combined with annotations covering safety and the schema covering params/pagination, an agent has nearly everything needed; only explicit page-size/pagination guidance is missing.

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 all four parameters are already documented with defaults and value constraints. The description echoes the status values and implies customer filtering but adds no syntax or meaning beyond what the schema provides; baseline 3 applies.

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?

Names a specific resource and scope ('booked invoices with a remaining balance'), which separates it from the draft-invoice sibling. It doesn't explicitly call out e-conomic_list_draft_invoices or list_customers, but the 'unpaid amount' framing makes the resource unambiguous.

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 the three filter modes ('all unpaid, only overdue or only not yet due') and cross-references get_invoice_pdf, but never states when to reach for this tool over list_draft_invoices or get_invoice. Guidance is implied through the filter description rather than explicit when/when-not routing.

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