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

The description discloses a lot of useful behavior: templates must only have the salutation changed, SMS uses shortLink and must be ≤70 chars, IM uses link, and the invitee must complete onboarding (not just register) for the daily chat quota to permanently increase. However, '首次可创建邀请码' states that the call may create an invite code, which is a state mutation contradicting readOnlyHint=true. The contradiction is disclosed rather than hidden, but it still misaligns with the declared annotation.

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 login gate, template constraints, and composition chain are front-loaded, and nearly every clause carries operational information. The text is dense and run-on, with bracketed shorthand and compressed abbreviations that slow parsing, but there is little outright 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, the description compensates by explaining the return fields (joined contains nickname only, no contact info; stats split into clicks/registrations/onboardings) and covers the auth requirement and side effects. For a zero-param read tool, the remaining gap is only the precise response shape.

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?

There are zero input parameters, so there is no parameter semantics burden and the baseline of 4 applies. Schema coverage is 100% and empty, and the description adds nothing about inputs because none exist.

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 concrete verb+resource: fetch my referral materials, namely 5 SMS and 2 WeChat templates plus an invite code/link. It is clearly distinct from siblings like list_my_invitations or create_guest_invite_link, although those alternatives are never named. The concrete nature of the tool's purpose is slightly obscured by the dense operational text around it.

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 '【组合链】额度不足→get_my_invite→用户分享→核对入驻' line gives an explicit trigger (chat quota exhausted) and the surrounding workflow. It also clarifies the division of labor: the user sends the message, the tool does not. No sibling alternatives are mentioned, keeping it below a 5.

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