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

The description discloses a non-obvious behavioral trait: 'Rewardful sends NO welcome email for API-created affiliates.' This is valuable context beyond what annotations provide. Annotations only signal destructiveHint=true, which is a generic safe-guess for a create tool and not contradicted. The description could mention rate limits or idempotency but does well on the welcome-email point.

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 terse sentences packed with distinct, useful information (affiliate vs referrer path, no welcome email, API endpoint). No filler; front-loaded with the primary action.

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?

Given no output schema, the description doesn't explain what is returned on success or error. It does cover the key creation semantics and a behavioral quirk. For a create tool with a rich input schema, it's nearly complete but leaves return-value ambiguity.

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 coverage is 100%, so the schema fully documents all 10 parameters. The description only highlights stripe_customer_id's variant meaning, adding a bit of semantic layer, but otherwise relies on the schema. Baseline 3 is appropriate.

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 states a clear verb+resource ('Add an affiliate') and even clarifies a variant behavior ('customer referrer, by passing stripe_customer_id'). It distinguishes itself from siblings like create_campaign or create_affiliate_link, though the distinction is inherent in the name rather than explicitly called out.

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 implies when to use the stripe_customer_id variant, but offers no explicit guidance on when to use this tool versus update_affiliate, get_affiliate, or other creation tools. The usage context is only lightly implied.

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