Receivables summary

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

Annotations already establish readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description still contributes the exact aging bucket boundaries (not yet due, 1-30, 31-60, 61-90, over 90) and the currency-level aggregation, which an agent cannot infer from the schema. It omits softer behavior like whether amounts reflect as-of-today or a snapshot, and excludes unapplied credits/paid invoices, which keeps it from a 5.

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?

One sentence, front-loaded with what is measured ('everything still owed on open invoices') followed by the grouping and totaling rules. Every clause adds information; nothing is padding.

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 does the job of explaining the return shape — buckets plus per-currency totals — which is exactly what an agent needs to plan a call. The remaining gap is the absence of an as-of date / data freshness note and confirmation that no parameters exist, which for a zero-input reporting tool is a minor rather than blocking omission.

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 tool takes zero parameters and the schema is empty, so there is nothing for the description to disambiguate; baseline 4 applies. A brief note that no filtering (customer, date, currency) is possible would have raised this to a 5, since an agent may otherwise assume it can scope the report.

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?

Names a concrete resource (amounts owed on open invoices) and a concrete shape (aged buckets, per-currency totals), so the agent knows immediately this is an aggregated receivables aging report. It implicitly separates itself from list_overdue_invoices (detail list) by saying 'grouped' and 'totaled', but never names a sibling, so it falls short of the top band.

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?

Usage is only implied: the aggregation language suggests 'use for an overview, not for per-invoice drill-down'. There is no explicit statement of when to pick this over list_overdue_invoices or customer_payment_history, and no prerequisites or exclusions are given.

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