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

With no annotations, the description carries the burden well: it discloses the required organizer/login role, that it bypasses the cross-event 7-day dedup, that invite-closed and decline backoff rules still apply, and that the caller should re-read SENT status afterward. It omits whether the sent DM can be revoked and what the message text contains.

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?

Short and front-loaded (role → pre-send confirmation → send), with no filler sentences. The semicolon-chained shorthand is efficient but borders on cryptic in spots such as '完成重读SENT', costing a little readability.

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 one-shot mutating send with no annotations and no output schema, the description supplies prerequisites, guardrails, side-effect disclosure (dedup bypass), and a post-action verification step. Only the message content/customizability is left unexplained, a minor gap at this complexity.

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 50%; activityRef is documented in the schema but invitationId is not. The description compensates by stating 'id取get_activity_invites', telling the agent exactly where to source the undocumented invitationId, which is real added meaning beyond the schema.

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 a specific verb and scope: immediately send a private message (私信) to exactly ONE SPEAKER candidate, and the title reinforces single-target intent. It is distinguishable from bulk/plan siblings via the '勿批量循环' clause, though the telegraphic Chinese makes the intended action slightly harder to parse than a plain verb+resource sentence.

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?

It gives concrete when-to-use conditions: confirm the target and the 名义 with the user first, then send to one candidate; and it explicitly excludes batch looping, routing multi-recipient work to a paced plan instead. The alternative is described by behavior ('多位用计划按间隔发') rather than naming set_guest_invite_plan, so the routing is clear but not fully explicit.

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