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

Annotations already flag destructiveHint=true, idempotentHint=false and openWorldHint=true, and the description goes well beyond them: it discloses that approval triggers configured rewards that may be paid out automatically (a real financial commitment), that a non-matching customer is written into every Preload-enabled program, and that per-customer outcomes are returned. That is exactly the side-effect detail an agent needs before invoking a destructive write.

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?

Front-loads 'WRITE:' and the endpoint, then layers consequence and return shape in a tight paragraph. Slight redundancy with the annotations on 'Not idempotent' and the raw POST path keeps it from being maximally efficient, but nothing is padding.

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?

No output schema exists, and the description compensates by naming the return outcomes (ReferralApproved, MemberPreloaded, Skipped). Combined with the destructive/financial consequences and the confirm gate, an agent has everything needed to call it safely.

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 100% and every parameter is documented inline, including the match-key role of email and the confirm gate. The description adds no syntax, format or default detail beyond that, 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?

Opens with an explicit verb-and-resource statement ('WRITE: reports a paying customer to Referral Rock') and immediately distinguishes the tool from sibling create_member/create_referral by describing the referral-matching behavior that only this tool has. An agent can tell exactly what this does without opening the schema.

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?

Describes the two decisive branches — matching email converts a pending referral, non-matching email preloads a member — which gives an agent the context needed to pick this over create_member or create_referral. It stops short of naming those siblings or stating explicit 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.