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

readOnlyHint=true already tells the agent this is a safe read, so the description need not restate the safety profile. It does add genuine value with the status_id legend (1-6) for interpreting returned records and the underlying endpoint (GET /api/v1/invoices), but says nothing about pagination behavior or result caps. Note the legend describes a returned 'status_id' field distinct from the schema's 'status' (active/archived/deleted) and 'client_status' parameters, which could momentarily confuse an agent.

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?

Three sentences, front-loaded with the purpose, then the status_id legend, then the endpoint. There is little waste, though the endpoint reference adds marginal value for an agent that never sees the transport layer.

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 list tool with no required parameters, no output schema, and readOnly annotations, the description plus 100%-covered schema gives the agent everything needed to call it correctly. Pagination mechanics live in the schema, so their absence from the prose is not a real gap.

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 every parameter is already richly documented in the schema; the baseline of 3 applies. The description adds only the payment-status vocabulary (paid/unpaid/overdue), which overlaps with client_status, and provides no format or syntax detail beyond what the schema already gives.

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 states a specific verb (list) and resource (invoices) and names the two filtering axes (client, payment status), so an agent understands what it returns. It does not explicitly differentiate itself from invoiceninja_get_invoice or the other list_* siblings, but the list verb makes the intent 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?

It implies the usage context by naming its filter dimensions (client and payment status), which is enough to infer common retrieval scenarios. However, it never states when to prefer this over get_invoice for a single record, and offers no exclusions or alternative-tool guidance beyond the implied filtering scope.

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