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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds the scoping semantics of "unpaid" (a non-zero balance) and hints at an implicit business context, but says nothing about ordering, result limits, or pagination.

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 short sentence, front-loaded with the verb and resource, with no filler. The trailing clause "for the business you picked" is the only slightly murky element, but it does not bloat the text.

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 zero-parameter read-only list tool with annotations covering safety and no output schema, this is nearly adequate. The gap is that the business scope is referenced but never explained, and ordering/limits are unstated, so an agent cannot fully predict what it will get back.

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, so the baseline is 4 and there is nothing for the description to clarify. "The business you picked" gestures at implicit session context but cannot be acted on through any parameter, so it adds no actionable parameter meaning.

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 gives a specific verb ("See") and resource ("invoices") qualified by a real condition ("still have a balance"), which effectively defines what "unpaid" means. It does not, however, distinguish itself from sibling list_overdue_invoices or list_recent_invoices, which an agent could easily confuse it with.

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?

There is no when-to-use or when-not-to-use guidance, and no mention of alternatives such as list_overdue_invoices or list_recent_invoices. The phrase "for the business you picked" implies a prior selection context but never states how or where that selection happens, leaving usage ambiguous.

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