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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavior: bucket boundaries, the New York default as-of date, that totals reconcile to the cent, that partial payments and credit memos are handled, that emails are drafts only and payments are never collected. It stops short of describing pagination or limits on invoice volume.

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?

The guidance is front-loaded in the first clause, which is correct, but the body is one sprawling sentence with a parenthetical synonym dump ('ar aging report template filled in') and feature stacking that strains readability. Some of the enumeration aids retrieval, yet phrases like 'polite past-due reminder email drafts from invoice facts' add words without adding decision-relevant meaning.

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 9-parameter, nested-object tool with an output schema, the description covers the inputs it needs to justify (invoices vs. file, as-of date, DSO inputs) and the outputs without needing to restate return structure. An agent has enough to decide to call it, pick the data source, and set the aging date.

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 100% and every parameter already carries an example and default, so the baseline is 3. The description adds a little beyond the schema, notably that a mixed-currency file is filtered to the single currency and that DSO derives from credit sales, but most of the 9 parameters are only exercised implicitly through the feature list.

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?

The description names a specific verb+resource (generate an accounts receivable aging report) and enumerates the exact outputs: Current/1-30/31-60/61-90/90+ buckets, per-customer and grand totals, DSO, reminder drafts, and PDF/Excel/CSV downloads. It explicitly excludes the adjacent-but-different task (accounts payable) and the accounting-software integration it does not perform. It never mentions the sibling generate_customer_statements, so an agent gets no help separating this from the statement tool.

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 opening 'Use this when the user wants...' clause plus the synonym set (aged receivables, 'who owes me money and how late') gives a clear triggering context, and 'Do not use for accounts payable (bills you owe)' is an explicit exclusion. It also states what the tool does not do (connect to accounting software, send emails, collect payments). The gap is that no alternative tool is named for overlapping cases such as customer statements.

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