app_start

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

Without annotations, the description provides useful behavioral details: it uses scrcpy when a session is active, falls back to ADB, and supports a force-stop prefix. However, it does not disclose what happens if the app is already running or error handling, which is a minor gap.

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 sentences long, front-loaded with the main purpose, and each sentence adds value: the first states the action, the second explains the method and a special feature. No wasted words.

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?

The tool is simple, and the schema covers parameters well. The description adds key behavioral context (fallback, force-stop). However, it could clarify whether serial is optional and what happens if the app is already running, but overall sufficient for a launch tool.

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?

Both parameters have descriptions in the schema (100% coverage), so the description adds little beyond confirming the force-stop prefix. The baseline of 3 is appropriate as the schema already clarifies the parameters adequately.

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's primary function: 'Launch an app on the device.' It specifies the resource (app) and verb (launch), and differentiates from sibling tools like app_stop (stop) and app_install (install) by focusing solely on launching.

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 does not explicitly state when to use this tool versus alternatives like app_stop or app_current. While it mentions internal behavior (session vs. ADB), it lacks guidance on choosing this tool over others for specific scenarios.

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