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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety is covered. The description adds real behavioral value by enumerating the returned content (code, link, share/discount, stats breakdown, recent commissions and payouts, referrer status), which matters since no output schema exists.

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?

Front-loads usage triggers, then lists returned data in one dense but purposeful sentence; two sentences with no filler. The parenthetical stat list is heavy but each item is informative, so it stops short of a 5.

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 no-argument, read-only, closed-world tool with annotations covering safety and no output schema, the description exhaustively describes the returned fields so the agent knows what to expect. Nothing needed to invoke or interpret the call is missing.

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 there is no parameter surface to document; the baseline for a no-arg tool is 4. Nothing in the description could add parameter meaning.

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 (retrieve) and resource (referral code, link, earnings, stats, commissions, payouts, referrer) so an agent knows exactly what comes back. The example query 'what is my referral code' implicitly separates this read from the write siblings set_referral_code and claim_referral_code, though it never names them explicitly.

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?

Opens with 'Use for ...' and three concrete user phrasings, giving clear when-to-use context. No when-not guidance or explicit alternative routing (e.g. pointing to set_referral_code for changes), which keeps it short of a 5.

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