Age the open invoices

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

No annotations are provided, so the description carries the full disclosure burden. It does reveal useful behavior: aging buckets, DUE-date basis, per-client/currency aggregation, inclusion of invoice-level rows, and a 'Free' cost signal. However, it does not explicitly state whether the operation is read-only, what exact response shape is returned, or any limits beyond the schema.

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?

Two efficient sentences plus a single-word cost note. The action and bucket definitions are front-loaded, and the sibling differentiation is stated without any filler.

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 reporting tool with no annotations and no output schema, the description gives enough context to select and invoke it correctly: what it computes, at what date, per what dimensions, and how it differs from the sibling. It could be more complete about exact return fields or side effects, but these are minor for this apparent read-only aging report.

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?

The input schema already documents all four parameters with 100% coverage, so the baseline is 3. The description reinforces client/currency and as-of date relevance, but adds no parameter-level detail beyond what the schema already provides.

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: 'Age open invoices into 0-30, 31-60, 61-90 and over 90 days past DUE date.' It also defines scope ('per client and currency, with the invoices themselves') and distinguishes itself from statements_report, so an agent can tell them apart immediately.

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 names the alternative tool ('statements_report') and contrasts its behavior ('rolls up the whole book instead'). The word 'instead' makes the when-not-to-use clear: use this tool when per-client/currency invoice detail is needed, not a whole-book rollup.

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