Launch Phone Link

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

Beyond the annotations (idempotentHint=true, destructiveHint=false), the description discloses the protocol handler used ('ms-phone:'), the timing behavior ('wait a few seconds'), and the return shape. These add valuable context for an agent deciding whether and how to call it.

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 compact and front-loaded, stating the main action first, then mechanism, timing advice, and return format. Every sentence earns its place and there is no redundant phrasing.

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 zero-parameter launcher with no output schema, the description covers the action, the underlying mechanism, the wait-before-other-tools caveat, and the response structure. Nothing an agent needs to invoke it correctly is missing.

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?

The tool has zero parameters and the schema description explicitly states 'No parameters required,' giving 100% coverage. With 0 params, the baseline is 4; the description adds no unnecessary parameter detail, and none is needed.

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 states a specific verb and resource: 'Launches the Phone Link app if not already running.' This clearly distinguishes it from sibling tools, which are getters or messaging actions. The title and description align without ambiguity.

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?

The description gives sequencing guidance: 'Wait a few seconds after calling this before using other tools,' which implies this should be called before other Phone Link tools. It does not explicitly name alternatives or state when not to use it, but the launch is a clear prerequisite for the sibling operations and the 'if not already running' condition provides context.

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