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

Annotations already cover the read-only safety profile, and the description adds real behavioral context beyond them: it reads only currently-open items rather than historical snapshots, explains as_of_date semantics, and discloses the no-due-date fallback (aged from issue date, surfaced in aged_from_issue_count). This is substantive data-semantics disclosure.

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?

Four tight sentences with the purpose front-loaded and no filler; each clause adds information. The trailing 'Read-only' lightly duplicates the readOnlyHint annotation, a minor redundancy.

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?

An output schema exists, so return values need not be re-explained, and the description still names an output field (aged_from_issue_count). It covers behavior and the key date parameter sufficiently for a read-only report; only currency and the nested id wrapper are left to the schema.

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 only 25%, so the description must carry parameter meaning. It explains asOfDate semantics well and implies the side parameter via AR/AP wording, but says nothing about currencyCode or the nested companyId wrapper. Partial compensation is worth a mid score.

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+resource ('aging' report of open AR/AP balances) and enumerates the exact buckets returned, which separates it cleanly from sibling reports like trial_balance or balance_sheet. An agent can identify the resource and scope 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?

The description implies when the report applies (open AR/AP balances by bucket) and clarifies that as_of_date only affects how overdue items are counted, which guards against misuse. It never names an alternative report or states an explicit when-not-to-use condition, leaving selection against siblings implicit.

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