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

Annotations provide no real safety profile (all hints false/absent), so the description carries the burden. It adds useful facts: buckets are based on DUE date, invoices themselves are returned, and the tool is free. However, it does not state whether this is a pure read/report operation, whether any state changes occur, or any auth/rate-limit implications.

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 efficiently written sentences front-load the core aging logic and output, then close with a clear sibling distinction. No filler or redundant restatement of the title.

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 list/report tool with no output schema, the description conveys the essential return content ('the invoices themselves'), the aging bucket boundaries, and the main alternative. It could be more complete about output structure, ordering, or limit behavior, but the key calling context is present.

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%, so the schema already documents as_of, limit, client, and currency. The description reinforces the client/currency/date dimensions but adds no meaning the schema does not already provide.

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 specifies the operation ('Age open invoices'), defines the output (buckets by days past due, per client/currency, with invoices themselves), and names the distinguishing sibling (statements_report), making the tool's purpose immediately clear.

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 explicitly contrasts itself with statements_report, telling the agent to use the sibling when the whole book is needed in rolled-up form. It also mentions the per-client/currency granularity, but it doesn't address other siblings like statement_build or statement_text.

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