Close a dedicated virtual account

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

Annotations already flag destructiveHint=true and readOnlyHint=false, so the description adds real value on top: the downstream effect (account stops receiving money), the guard error for dynamic accounts, and the no-op behavior for already-closed accounts returning unchanged. It doesn't say whether closure is reversible or what the response body contains, which keeps it below a 5.

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?

Short and front-loaded, with the error case and the idempotent no-op placed where an agent will read them. The first sentence merely restates the title before the useful sentence that follows, a small 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?

For a destructive, no-output-schema mutation, it covers the effect, the failure mode, and the already-closed case, which is most of what an agent needs. It omits any return-value indication and why `reason` is required, leaving a slight gap.

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 coverage is 67%; `id` and `idempotency_key` are documented in the schema, but `reason` has no description anywhere. The description adds no meaning about any parameter, so it neither compensates for the gap nor adds beyond the schema — baseline 3.

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 specific verb and resource ("Close a dedicated virtual account") and immediately defines the effect: it stops receiving money. The qualifier "dedicated" separates it from dynamic accounts and from the create/list/get virtual account siblings.

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?

Gives a clear when-not rule: dynamic accounts can't be closed this way and are closed by their payment, with the exact error surfaced (`400 invalid_operation`). It lacks an explicit named alternative tool for the dynamic case, but the routing condition is unambiguous.

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