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

With readOnlyHint already declared, the description adds real context: result ordering ("Recent first") and the exact per-invoice projection (id, number or "Borrador" for a draft, date, total, status). It does not say whether results are capped by the limit parameter or truncated, which is the one behavioral gap that matters for a list tool.

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?

Dense but front-loaded: purpose, then filters, then ordering, then return shape, then the sibling redirect. No filler sentences and every clause carries information an agent needs.

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?

There is no output schema, yet the description fully specifies the return shape at line granularity, so the agent knows what it will receive. Combined with ordering and filter semantics, nothing essential for a correct call 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 only 25%, so the description must compensate, and it largely does: it enumerates status filters, explains that query searches not just number/reference/notes/customer but also line descriptions (a real behavior the schema does not convey), and implies year filtering. It omits the limit parameter entirely (default 20, max 100), leaving one of four params undocumented.

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 and resource ("List invoices") plus the scoping domain ("for the user's contix account"), and explicitly contrasts with the sibling get_invoice. An agent can distinguish this list/search tool from the single-invoice fetch without opening either 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?

Explicitly routes the agent to get_invoice when full line items or the Veri*factu hash are needed, which is the main ambiguity for a invoices listing. However there is no guidance on when to prefer list_invoices vs. other listing tools (list_quotes, list_expenses) and no mention of limits/pagination strategy.

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