send_imessage

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

Without annotations, the description discloses that sending uses osascript, that success returns a confirmation string, and that errors occur if Messages is not open or recipient not found, offering good behavioral insight.

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 extremely concise, structured with clear Args, Returns, and Raises sections, with every sentence contributing essential information.

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 simple two-parameter tool with an output schema, the description covers purpose, parameters, return value, and errors, making it fully complete.

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?

Despite 0% schema coverage, the description fully enriches both parameters: recipient format (E.164 or email) and message content (text with newlines preserved), far exceeding the bare schema.

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 clearly states the tool sends an iMessage or SMS via the macOS Messages app, specifying the action and resource with precision.

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?

Provides explicit format constraints for recipient (E.164 or email) and explains error conditions, but lacks explicit when-to-use or when-not-to-use guidance, though no siblings exist.

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