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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful output detail, including credited amounts and balance due, but does not mention pagination, ordering, or whether the result is limited in any way.

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 sentences with the main action front-loaded and no filler. The list of returned fields is compact. The phrase 'by number' adds minor ambiguity but does not significantly hurt comprehension.

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 operation with four optional filters and no output schema, the description covers the core return fields and available filters. It lacks pagination/ordering details, but annotations cover the safety profile and the schema covers date formats, making this reasonably complete.

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 50%, covering from/to but not client or status. The description names status, client, and date range as filters, adding some meaning beyond the schema, but it does not clarify the client parameter's format or semantics beyond the field name.

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 uses a specific verb ('List') and resource ('invoices'), and enumerates the fields returned (client, dates, currency, totals, status, balance due). It is clear what the tool does, though it does not explicitly differentiate itself from siblings like invoice_get or invoice_pdf, and the phrase 'by number' is slightly ambiguous.

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 states the filtering dimensions: status, client, and date range, which implies when to use this tool. However, it does not explicitly contrast it with invoice_get for single-invoice lookup or overdue_report for overdue-focused reporting, so usage guidance relies on inference.

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