Launch App

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

Annotations already disclose the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description only needs supplementary context. It adds the discovery path for package names but says nothing about what happens if the app is not installed, whether the app is foregrounded, or any latency/state effects of launching.

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?

Three short sentences, action stated first, followed by usage and the prerequisite lookup. Every sentence carries information with no filler.

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?

There is no output schema, so return behavior is not required, and the description covers the core action and how to source the required packageName. It omits failure/edge-case behavior (invalid package, unavailable device), leaving minor gaps for a simple action 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?

Schema description coverage is 100%, so all three parameters (device, locale, packageName) are documented in the schema itself. The description's pointer to mobile_list_apps for the package name adds marginal value but no syntax, format, or constraint detail beyond the schema, matching the baseline for fully-covered params.

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?

States a specific verb ('Launch') and resource ('an app on mobile device'), which cleanly separates it from siblings such as mobile_terminate_app, mobile_install_app, and mobile_open_url. An agent can identify the tool's action without opening the schema.

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?

'Use this to open a specific app' gives clear positive usage context and explicitly routes the agent to mobile_list_apps for obtaining the package name. It stops short of naming when-not-to-use cases (e.g., opening a URL vs. launching an app, or batching), so it falls short of a full 5.

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