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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false. The description adds important behavioral context beyond annotations: it requires a Last Price credential with billing read scope and a claimed workspace, and it warns that self-registration sandbox keys get 403 until the workspace is claimed.

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?

The description is two sentences, front-loading the purpose and fields before the credential and workspace requirements. Every sentence carries useful information, with no repetition or 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?

There is no output schema, so the description appropriately names the main fields returned. It also includes the authorization scope and workspace-claim caveat that an agent needs before calling this read-only single-payment 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?

The schema has 100% description coverage for the single payment_id parameter, including that it is the id from a list_payments result. The description does not add further parameter syntax or meaning beyond what the schema already provides, so this is the baseline case.

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 and resource: 'Read one payment', and enumerates the fields returned (invoice, customer, amount, currency, status and method). The singular 'one payment' distinguishes it from list_payments and the read framing distinguishes it from create_payment and refund_payment.

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 description implies usage by saying it reads one payment, which fits fetching a single known payment. However, it does not explicitly name alternatives such as list_payments for browsing or state when not to use this tool. The credential and workspace notes are prerequisites rather than alternative-selection guidance.

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