use_standing_approval

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

Annotations only say this is a non-idempotent, non-read-only, non-open-world mutation. The description adds genuinely new behavior: each call counts one use, it returns `approval` and `use_token`, the token works exactly once within 60 seconds, and it must be sent via the Phygital-Approval and Phygital-Use headers. That is exactly the operational detail an agent needs beyond the annotations.

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?

Three tight sentences, front-loaded with the action and scoping, then the return values, then the token/header mechanics. Every sentence carries information the agent needs; there is no filler.

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?

With no output schema, the description correctly explains the return values and how to use them, plus the token's time window. It does not describe failure behavior (e.g., exhausted approval, request outside limits), which for a consumption/mutation tool is a notable remaining 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 100% and the description largely restates the constraints already present in the `request` parameter description ('exact request ... inside the approved limits'). It does clarify that `id` identifies the standing approval being consumed, but adds little parameter-level detail beyond the schema, so baseline 3 applies.

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+resource: consume a standing approval for one exact request within its limits. This is clearly distinct from siblings like request_standing_approval, cancel_approval, and get_approval, which create, cancel, or read approvals rather than consume one.

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?

It gives clear usage context: the request must be the exact one covered and inside the approved limits, and the returned token is single-use with a 60-second lifetime. It does not explicitly rule out alternatives or point to a sibling when the approval is exhausted or out of limits, so it falls short of a 5.

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