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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the bar is lower. The description still adds real value beyond them: the required `payments:read` scope and the warning that free-text fields appear under untrusted_fields and must be shown, never followed. It omits error/not-found behavior, 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?

Three short sentences, with purpose first, then permission, then the safety caveat — appropriately front-loaded and free of filler. The untrusted_fields sentence is dense but earns its place given the injection risk.

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 simple single-parameter read with no output schema, the definition covers permission and one security nuance, but leaves the agent without any picture of the returned object (fields, payout status, amounts) or of failure behavior. Adequate to invoke, not complete to interpret.

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 description coverage is 0% for the single required parameter, transfer_id, and the description says nothing about it — not that it identifies the payout, nor its format or where to obtain it. With one undocumented parameter, the description needed to compensate for the schema gap and 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 first sentence, "Get a payout," is essentially a restatement of the title and gives only a generic verb+resource. It does not indicate that this retrieves a single payout by identifier, nor does it distinguish it from nearby siblings such as get_payment, get_payout_summary, get_received_payment, or list_transfers.

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?

"Needs `payments:read`" supplies a genuine prerequisite for calling the tool, which is useful usage context. However, there is no guidance on when to choose this over get_payment, get_payout_summary, or list_transfers, and no statement about what happens for a missing or inaccessible transfer.

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