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

Annotations already mark the operation as read-only and idempotent. The description adds the authentication requirement and clarifies that the returned data belongs to the currently authenticated account, which is useful context beyond the structured 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?

The description is extremely concise, stating exactly what is returned and the required authorization in two short sentences. Every word serves a purpose and the most important information is front-loaded.

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 the tool's simplicity, the read-only annotations, and the presence of an output schema, the description covers all necessary context. The only extra requirement, authentication, is explicitly stated, making the definition complete for a zero-parameter retrieval tool.

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 has zero parameters, and the schema fully covers this with an empty properties object. Per the baseline for no-parameter tools, the description does not need to compensate for missing parameter documentation.

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 clearly identifies the resource: this account's referral code and shareable referral link. While there is no explicit verb in the description, the title supplies 'Get', and the resource is distinct enough from sibling tools to avoid ambiguity.

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 description states an important prerequisite, the `Authorization: Bearer zs_...` header, which helps the agent know when the call can be made. It does not explicitly discuss when to use this tool versus alternatives, but the referral-link resource is unique among the listed siblings, so the omission is minor.

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