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

Annotations already cover read-only, idempotent, non-destructive, closed-world behavior, so the bar is lowered. The description nonetheless adds real context beyond the annotations: the receipt is 'signed,' it is publicly verifiable without Regent, and the token should not be surfaced to the user — a useful sensitivity warning absent from the structured fields.

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 sentences, both earning their place, with the core resource definition front-loaded and the handling directive trailing. The first sentence is dense with nested clauses but stays readable and avoids 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 responsibly describes the returned contents (payment details, recipient, terms version, verify URL). It omits only edge cases such as an unknown or non-completed decision id, which is a minor gap for a single-record read.

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 0% and there is one parameter, so the description must carry the load. It identifies the argument as a decision id with the 'dec_…' prefix and ties it to 'one of your completed payments,' giving format and provenance that the bare schema string does not.

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 names a specific verb+resource ('the signed receipt of one of your completed payments') and enumerates what it returns (what was paid, to whom, terms version, verify page), so an agent can tell exactly what it retrieves. It does not explicitly differentiate itself from siblings such as approval_status or pay, but the resource is distinctive enough that confusion is unlikely.

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 context implicitly (fetch for a completed payment by decision id) plus an explicit behavioral directive: 'Show the person the verify link rather than the token.' That tells the agent how to handle the result, though it names no alternative tools or when-not-to-use conditions.

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