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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds substantial context beyond them: management-permission requirement, outbound messaging side effect, per-person SENT/ALREADY_SENT/FAILED return codes, the instruction not to resend a whole batch on partial failure, and the caveat that delivery ≠ acceptance/registration. This is rich behavioral disclosure for a mutation tool.

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 【需管理权限·会发信】 prefix front-loads the most decision-relevant facts, and each subsequent clause carries distinct information (batch limit, status codes, preview flow). It is dense and semicolon-packed, but essentially no sentence is wasted.

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 batch mutation tool with no output schema, the description covers the safety/permission profile, return-status semantics, partial-failure handling, and the confirm-after-preview protocol. Gaps remain around what activityRef identifies and the purpose of note, but the core call contract is adequately conveyed.

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 explains the critical preview/previewHash flow and the userIds batch cap, but leaves activityRef (the target reference) and note (max 600 chars) entirely unexplained, so coverage is only partial.

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 title and opening clause state a specific verb+resource: sending guest-material invitations to designated App users. It indirectly distinguishes itself from the plan-based sibling via '不建自动计划' (does not create an auto plan, i.e. use set_guest_invite_plan for that), but the differentiation is implicit rather than named.

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?

Gives concrete operating context: batches of ≤20, large rosters confirmed in batches, and private activities granting named audiences separately. The preview-first workflow ('默认预览；确认后同参+previewHash、preview=false') tells the agent exactly when and how to proceed, though no alternative tool is named explicitly.

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