set_typing

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

Discloses auto-expiry after ~15 seconds, silent ignorance if recipient disables indicators, and no error for unsupported groups, fully transparent without relying on annotations.

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?

Dense but well-structured; every sentence adds value. Slightly longer than necessary but front-loaded with primary action.

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?

Covers behavior, limitations, auto-expiry, cancellation, and silent failure completely for a simple tool without output schema.

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?

Adds context beyond schema: explains stop parameter default and purpose, and implicitly reinforces E.164 format for recipient. Schema coverage is 100%, so a baseline of 3 applies, but description enriches understanding.

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 identifies the tool as sending a 'typing…' indicator to a Signal contact, distinguishing it from siblings like send_message by specifying its unique purpose and scope (one-to-one DMs only).

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?

Explicitly states when to use (before send_message), when not to (groups, tight loops), and how to use stop=true for early cancellation, providing clear context and alternatives.

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