Detects whether the Android screen is on or locked and returns state variables, enabling workflows to branch or halt based on screen status.
读取屏幕是否亮着、是否锁屏。输出：screen_on, screen_locked, screen_state_success, screen_state_error。字符串参数支持 ${var} 插值；结果以变量快照 JSON 返回。
| Name | Required | Description | Default |
|---|---|---|---|
| require | No | 执行后要求为 true 的变量名（如 click_success），不满足按出错处理 | |
| on_error | No | 节点出错时：skip=跳过继续（默认），stop=停止整个工作流 | |
| node_timeout_ms | No | 单节点超时毫秒，0=不限；默认 30 分钟 |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description has to carry the full burden of disclosure. It does useful work by naming the four output variables and saying that results come back as a variable snapshot JSON. It does not say whether the call is read-only, whether it needs any permissions, or how long it takes.
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 short and front-loaded: the read purpose comes first, followed by outputs and the interpolation note. Every sentence adds information. The wording is dense but not padded.
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, but the description compensates by enumerating the return variables (screen_on, screen_locked, screen_state_success, screen_state_error). Parameters are fully covered by the schema. The remaining gap is the absence of any pointer to alternatives among the many screen-related siblings.
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 the schema already documents require, on_error, and node_timeout_ms, and a baseline of 3 is appropriate. The one addition beyond the schema is that string parameters support ${var} interpolation, which is genuinely useful. The description does not explain which parameters the interpolation applies to.
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 opens with a specific verb+resource: reading whether the screen is on and whether it is locked. That is enough for an agent to know what the tool does. However, it does not distinguish the tool from related siblings such as ACTION_READ_SCREEN, ACTION_SCREEN_WAKE, or mini_screen_status, so the agent has to infer the difference.
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 says what the tool reads but never says when to use it, when not to use it, or which sibling to choose instead. With several screen-related siblings, an agent that wants to know whether the screen is lit receives no guidance on whether to use this tool, ACTION_SCREEN_WAKE, or mini_screen_status.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.