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

Despite minimal annotations, the description discloses important behavior beyond structured fields: management permission is required, messages will actually be sent, per-user SENT/ALREADY_SENT/FAILED statuses are returned, partial failure should not trigger whole-batch resend, and delivery is not acceptance or registration. It also explains the preview/confirmation mechanism and that it does not create an automatic plan.

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 compact and front-loads the most important facts: permission need and message-sending side effect. Every clause adds operational value, including batch limits, status handling, preview behavior, and confirmation rules.

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 mutation tool with no output schema and minimal annotations, the description covers the critical workflow: permission, sending behavior, batch limits, per-user outcomes, partial failure handling, and previewHash confirmation. It is not fully complete because activityRef and note remain unexplained, but the core invocation behavior is clear.

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 description coverage is 0%, so the description must carry parameter meaning. It usefully explains the userIds batch limit, preview default, and previewHash confirmation flow, but it does not explain activityRef or note, leaving important parameters undocumented in both schema and description.

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 action: sending guest-material invitations to App users, with a batch limit and permission requirement. It also distinguishes itself from plan-creation behavior by saying it does not create an automatic plan, though it does not explicitly name the many other invite-related siblings.

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 clear usage context: each batch is capped at 20 App users, large lists must be confirmed in batches, private activities require separately authorized named audiences, and the default is preview. It lacks explicit routing to alternative tools such as send_guest_invite_now or set_guest_invite_plan, but the exclusions and workflow constraints are useful.

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