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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered by structured data. The description adds useful context about what is returned (line items, payments, totals, balance), but says nothing about pagination behavior or result-size limits beyond what the schema already carries.

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?

Purpose and filter scope are front-loaded, followed by the sibling routing hint; two sentences, no padding. The parenthetical field list is long but each item earns its place by describing the return shape in the absence of an output schema.

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?

With no output schema, the description usefully discloses the returned fields including nested line items and payments, and lists the available filter dimensions for a 7-param, all-optional tool. It is complete enough to call correctly; only pagination/ordering behavior is left implicit.

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 all seven parameters (page, page_length, created_from/to with their time-boundary semantics, invoice_ids, location_ids, voided_only) are already documented. The description only restates the filter dimensions at a high level, adding no syntax or default details beyond the schema, so the baseline of 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?

States a specific verb+resource ('List invoices'), enumerates what each record includes (line items, payments, and the fields in parentheses), and scopes it to three filter axes. It also distinguishes itself from the sibling path for per-client invoices, so an agent can identify it without opening the schema.

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?

Gives an explicit alternative and the condition that selects it: 'For one client's invoices use get_client with include_invoices.' That is real routing guidance, though it does not contrast with the other list_* siblings (payments, appointments) that could overlap with invoice-adjacent queries.

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