open_app

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

No annotations are provided, so the description carries the disclosure burden. It does disclose the allowlist restriction and the need to consult list_apps, which is useful. However, it does not describe what happens for disallowed apps, whether launching has side effects on the current device state, or how the optional device parameter affects behavior.

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 short sentences with no filler. The action and examples are front-loaded, and the allowlist constraint is stated immediately afterward. Every sentence earns its place.

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 launch tool, the core purpose and restriction are present, and an output schema exists so return values need not be described. However, the optional device parameter is unexplained, and the description does not mention any alternative tools such as open_settings. This is adequate but has clear gaps.

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 0%, so the description must compensate. The 'name' parameter is clarified with examples, but the optional 'device' parameter is left entirely unexplained. Since one of the two parameters has no semantic guidance, the description only partially compensates for the missing schema descriptions.

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 clear verb-object structure ('Open an app by name') with concrete examples ('youtube', 'chrome'), and it clarifies the tool only operates on allowlisted apps. This distinguishes it from related sibling tools like list_apps, which enumerates apps rather than launching them.

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 a clear precondition: only allowlisted apps can be opened, and the agent should call list_apps to discover them. It does not explicitly list alternatives or exclusions, but the context is sufficient for an agent to decide when to use this tool.

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