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

Annotations already establish readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered. The description adds real value beyond that by disclosing what the response contains (link, referral count, commission rate, credits earned) — important because there is no output schema to reveal the return shape.

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 short sentences, front-loaded with the purpose and followed by the payload breakdown. The first sentence duplicates the title verbatim, which is mild waste, but nothing else is extraneous.

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 zero-parameter, read-only, account-scoped tool with no output schema, the description supplies the missing return-value context an agent needs. Scope is implicitly the authenticated caller's own program; the description does not explicitly say whether it works when no referral program exists, which is a minor gap.

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?

The tool takes zero parameters, so the baseline of 4 applies. There is nothing to mis-specify, and the description correctly implies no input is required by framing the call as retrieving 'your' program.

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+resource ('Get your referral program') and then enumerates the concrete payload (referral link, referral count, commission rate, credits). It is unambiguous which resource it addresses, though it does not explicitly contrast itself with any sibling — which is acceptable here since no sibling covers referrals.

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?

Usage is implied: call this to read the caller's own referral program data. There is no explicit when/when-not guidance and no named alternative, but no plausible alternative exists among the siblings, so the omission is low-risk rather than misleading.

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