Send iMessage

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

No annotations are present, so the description carries the behavioral disclosure burden. It usefully reveals the default pacing and the existence of an instant mode, plus the transport line. However, it does not disclose side effects, return behavior, or constraints such as message_effect being instant-only, which are either left to the schema or unstated.

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 two concise sentences with no filler. It front-loads the action and recipient details, then follows with the mode selection guidance that an agent needs most.

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?

Between the description and the fully documented schema, an agent has enough to invoke the tool correctly: recipient format, message/media combination, send mode, and media URL constraints. The main gap is that no output schema or return-value explanation is provided, and there is no explicit link to check_imessage_capability before sending.

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 100%, so the schema already documents all five parameters. The description mentions send_mode and text/media but adds no meaning beyond what the schema's parameter descriptions already provide, so the baseline of 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?

The description uses a specific verb ('Send'), names the exact resource ('text and/or media iMessage'), and specifies the recipient format (E.164) plus the delivery channel ('Blue Reacher line'). This makes it clearly distinct from sibling tools like get_message_status, list_conversations, and check_imessage_capability.

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, actionable guidance: drip pacing is the default, and passing send_mode 'instant' is how to dispatch immediately. It does not explicitly name sibling alternatives or state when not to use this tool, but the sending context is clear enough for an agent to select it appropriately.

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