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

With readOnlyHint=true already declaring a safe read, the description still adds value by disclosing the response shape: the payout comes with the affiliate and the commissions it bundles. Since no output schema exists, that return-content detail is genuinely useful 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?

Two compact sentences with the primary action ('Fetch a single payout by id') front-loaded and the response contents following. The trailing 'Rewardful: GET /v1/payouts/:id' is mildly redundant but maps the tool to an endpoint, which is a defensible use of space.

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 one-parameter GET with annotation coverage and no output schema, the description supplies the essential missing piece: what the returned payout includes (affiliate plus bundled commissions). Nothing critical to calling it correctly is absent, though return formatting and error behavior remain unstated.

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?

A single parameter (payout_id) is documented at 100% schema coverage as a UUID, so the schema carries the semantics. The description only repeats 'by id' and adds no format, validation, or lookup nuance, so the 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 and resource ('Fetch a single payout') and scopes it to one record by id, which implicitly contrasts with the sibling rewardful_list_payouts. It stops short of naming the alternative, so sibling differentiation is inferred rather than explicit.

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 phrase 'by id' implies usage: fetch one payout when you already have its identifier. However, there is no explicit when-to-use guidance, no exclusions, and no named alternative (e.g., list_payouts for enumerating payouts). Usage is only implied.

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