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

With no annotations, the description carries the full burden. It discloses the key behavioral trait that `as_of` reconstructs historically-open items so results agree with a historical aging report, and it implies a read operation. But it omits auth/permission requirements, pagination, and confirmation that the operation is non-mutating.

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 short passages with the core identity front-loaded and the `as_of` nuance following. Efficient, though the heavy backtick/typographic formatting adds noise without adding 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 read tool with no output schema and no annotations, the description conveys what comes back ('open items + totals') and the `as_of` semantics. It stops short of describing the totals' composition, result shape, or limits, leaving modest gaps for a financial drill-down tool.

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 0%, so compensation is required. The description explains the one non-obvious parameter, `as_of`, in real depth (historical reconstruction semantics, parity with the aging endpoint), but leaves `company_id` and `counterparty_id` purely reliant on self-explanatory names.

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 states a specific resource and scope: 'One customer's open items + totals', and frames it as 'the aging row's drill-down', which lets an agent distinguish it from broader statement/report siblings. It is a noun phrase rather than a verb+resource, but the returned content is unambiguous.

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 parenthetical 'the aging row's drill-down' implies when to reach for it (drilling into a customer's aging row), which is useful contextual usage guidance. However, it names no alternative sibling and no explicit when-not condition, so the routing signal remains implicit.

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