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

With destructiveHint=true already declared, the description adds a genuinely non-obvious behavioral fact: Rewardful sends NO welcome email for API-created affiliates. That is exactly the kind of consequence an agent should surface. It stops short of noting idempotency, duplicate-email handling, or auth requirements.

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 tight sentences, front-loaded with the action and the referrer branch, and the API endpoint is appended after the substantive content. No 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?

For a 10-param creation tool with full schema coverage and no output schema, the description covers identity, the referrer variant, and the email side effect. It leaves the success response shape and conflict behavior unaddressed, but as a create tool it is largely complete.

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%, so all ten parameters including stripe_customer_id, state, and token are documented in the schema itself. The description only re-frames stripe_customer_id, adding little beyond structured data, 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 ('Add an affiliate') plus a scoped variant ('customer referrer, by passing stripe_customer_id'). This clearly separates it from sibling creators like rewardful_create_affiliate_coupon and rewardful_create_affiliate_link.

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 signals one branch of usage (referrer vs affiliate via stripe_customer_id) but gives no guidance on when to prefer this over rewardful_update_affiliate or how to handle an affiliate that already exists. Usage is implied rather than stated.

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