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

Annotations already declare the tool read-only and non-destructive, so the safety profile is covered. The description adds that the tool returns a referral code and earnings summary, but it does not disclose any behavioral nuances beyond that. No contradiction with 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 six words and contains no filler. It front-loads the resource and the return content, making it easy to scan.

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 tool with an output schema, the description is largely complete: it states what the tool returns and annotations cover side effects. It could be slightly clearer about whose referral stats are being reported (e.g., the current user), but the complexity is low enough that this 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 has zero parameters, so there is nothing for the description to document. The baseline of 4 applies because no parameter semantics are needed and the description does not introduce any conflicting parameter expectations.

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 names the resource (referral) and the content of the result (referral code and earnings summary), which distinguishes it from credit status or gift breakdown siblings. It lacks an explicit action verb such as 'get' or 'view', so it falls just short of the strongest purpose clarity.

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?

There is no guidance on when to use this tool versus alternatives. With many credit-related siblings like ucode_credits_status, ucode_credit_gift_breakdown, and ucode_credit_referral_redeem, the description does not help an agent select the correct one.

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