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

The description goes well beyond the annotations by disclosing the lazy generation of the referral code on first call, the login requirement, and that joined only exposes nickname/status without contact info. It also warns against rewriting the canned copy and explains shortLink vs link constraints, giving the agent critical operational context.

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 dense but well-structured with headed sections and front-loaded trigger conditions. Every block carries actionable guidance—copy constraints, message-length limits, stats semantics, and follow-up workflow—so no sentence feels like filler.

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?

With no output schema present, the description compensates thoroughly by enumerating the returned fields and their business meaning. It covers the full end-to-end usage flow, including how to choose, personalize, deliver, and later verify referral outcomes, leaving no obvious gap for correct invocation and interpretation.

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?

This tool has zero parameters, so the baseline is 4; there is no input ambiguity to resolve. The description instead adds valuable output semantics—template labels, stats fields, and link selection—which is more than sufficient for a no-parameter tool.

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 specifies what the tool returns: 5 SMS templates, 2 WeChat templates, an exclusive short link, and three-part stats (opens/registrations/onboarded). It anchors the purpose to concrete user intents like inviting friends or needing more opening quota, which separates it from siblings such as get_my_brief.

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 '何时用' section gives explicit trigger phrases and conditions. The '组合链' section prescribes the actual workflow: choose a template by label, send it from the user's phone, then check stats.onboarded later. It also explicitly redirects quota checks to get_my_brief or chatQuota, naming the alternative tool.

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