messages_send

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

With no annotations, the description carries the full burden. It usefully discloses the confirm gating (preview without it), that chat_id is verified against the Messages database, and that multi-recipient sends need confirmation — but it omits permissions/account requirements, irreversibility of sending, and any return behavior. Partial coverage for an irreversible mutating action.

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?

Three tight sentences, front-loaded with the core action, then the addressing options, then the confirm caveat. No filler, every sentence earns its place.

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?

No output schema exists, but the description plus fully-documented schema cover addressing, confirmation, service selection and dry-run adequately for a send tool. Missing only peripheral details such as required permissions and confirmation of what a successful send returns.

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 100%, so the schema already documents all seven parameters including the E.164 and chat GUID formats. The description reinforces the addressing formats with examples but adds little beyond what the schema provides, so the baseline 3 applies.

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?

States a specific verb and resource (send an iMessage or SMS) and names the delivery medium, which cleanly separates it from sibling senders like mail_send. An agent can identify the operation 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?

Gives clear routing guidance for the two addressing modes ('to' vs 'chat_id') and states the condition that requires confirm=true for group/multi-recipient sends. It does not name alternatives or say when not to use it, but the context is sufficient to invoke correctly.

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