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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description still adds real behavioral information: results are ordered newest first, status is computed live (a sent invoice past its due date reads as overdue), and aggregate outstanding/overdue totals are returned. It does not mention pagination or the default/cap on result count.

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 sentence, front-loaded with the verb and resource, with no filler. Every clause (ordering, live status, totals, no-required-input) carries information an agent can act on.

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?

No output schema exists, so the description must describe the return payload — and it does: per-invoice live status plus outstanding and overdue totals. With only two optional parameters, no required inputs, and full annotation coverage, nothing material 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 50%: the status enum carries a description ("unpaid = sent, viewed or overdue") but limit is undocumented. The description is consistent with and reinforces the derived-status semantics of the status filter and explains the ordering that limit interacts with, but it never explains limit or its 25/100 default/cap. Baseline 3 is right given partial coverage.

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 concrete verb (read/list) and resource (the signed-in person's own invoices), plus scope-limiting details: newest-first ordering, live status, and outstanding/overdue totals. It clearly separates itself from the mutation siblings (create_invoice, send_invoice, mark_invoice_paid), though it never explicitly contrasts with the read-side sibling list_transactions, so an agent must infer the invoice-vs-transaction boundary.

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?

"Needs no details from the person" implies the tool is called with zero required arguments and is the natural read-side entry point, which is useful. However, there is no explicit statement of when to prefer this over list_transactions or when to follow up with mark_invoice_paid, so usage guidance is only implied.

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