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

With no annotations, the description must carry the behavioral burden; 'stats' implies a read-only operation, and the invite-link format is a helpful extra. But it says nothing about error behavior for a malformed address, whether the address must be a registered inviter, or what happens with an unbound address — gaps for a tool with zero annotation coverage.

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 tight clauses: the capability statement is front-loaded, followed by the concrete link template. No filler, though the metrics list is slightly dense in one sentence.

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 single-optional-parameter read tool with no output schema or annotations, the description covers both call modes and the practical link format an agent would need. Missing pieces are return shape and invalid-address handling, which keeps it from a 5.

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 0%, so the description must compensate. It does clarify that 'address' selects a single inviter's view and shows the expected address usage in the link format, adding real meaning. It still does not explain the accepted 0x-prefixed 40-hex format that the schema pattern enforces, leaving partial coverage.

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 specific resource (referral program stats) and enumerates the metrics returned: global slots/budget usage and, per-address, bound count plus earned/pending SHANIU. This is well beyond tautology. It does not explicitly contrast with shaniu_stats, so it falls short of a 5.

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 parenthetical '(with address)' implicitly tells the agent how to switch between global and per-inviter modes, which is useful usage guidance. However, it never names the alternative sibling (shaniu_stats) or states when-not to use this tool, so usage is only implied.

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