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

Annotations already mark this as destructive, non-read-only, open-world, and non-idempotent. The description adds substantial context beyond that: queued is not delivered, values must match the server snapshot, consent/permissions/expiry/allowance apply, and how to handle a lost response. No annotation contradiction.

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?

Five tightly packed sentences, front-loaded with purpose and followed by prerequisites, constraints, and recovery guidance. Every sentence carries operational information; no 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?

For a destructive SMS send with no output schema, the description covers prerequisites, validation, consent/permissions, expiry, allowance, and recovery well. It does not explain the return payload or describe event_id semantics, leaving minor gaps.

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 67%. The description adds meaning for preview_id and recipient_count by mapping them to the preview's audienceSize and requiring exact match with the server snapshot. It does not describe event_id, but that parameter is self-evident and the remaining schema descriptions cover the other fields.

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 opens with a specific verb+resource: queue the exact previewed SMS to opted-in event guests and hosts. It implicitly distinguishes from preview_sms_announcement by describing a post-review queue action rather than preview generation. An agent can identify the tool's function without opening the schema.

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 states the prerequisite context ('After host review') and required inputs (preview_id, exact message body, recipient_count, confirmed, event_updates_only). It also gives recovery guidance for lost responses. It stops short of explicitly naming when not to use it or an alternative sibling, so not a 5.

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