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's residual job is to disclose return shape; it does contribute something by noting line items and totals are included (useful since no output schema exists). It says nothing about pagination behavior, filtering capability, or whether results are scoped to a company, which is where the real ambiguity lies.

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?

A single compact fragment with no filler, but being a noun phrase rather than a verb-led sentence means the action is not front-loaded — the agent has to borrow the verb from the title.

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 zero-required-parameter list tool with no output schema, the description covers scope and payload but omits anything about result ordering, total counts, or that the query parameter is the intended way to narrow by status/date/customer. Adequate but with recognizable gaps.

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 page, pageSize, projectId, and the fairly intricate 'query' filter DSL are fully documented in the schema; the description only obliquely references the status filter through its status enumeration. Baseline 3 is appropriate since the schema does all the work.

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 fragment names the resource ('Sales invoices') and enumerates the statuses it covers, plus what payload it includes, but it never states a verb (the 'list' action comes only from the name/title) and gives no explicit contrast with close siblings such as bokio_list_supplier_invoices, bokio_list_credit_notes, or bokio_list_invoice_payments.

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?

There is no statement of when to use this tool versus alternatives — no mention of using bokio_get_invoice for a single record, or list_supplier_invoices/list_credit_notes for other invoice families. The reader must infer the selection rule from the sibling names alone.

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