screen_key

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

No annotations are provided, so the description carries the burden. It discloses the environment variable prerequisite and example key formats, which adds helpful context. However, it does not describe failure behavior, side effects, or what happens if the environment variable is not set.

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 a single sentence with examples, efficiently conveying purpose and prerequisite without unnecessary 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?

For a simple one-parameter tool, the description covers purpose, prerequisite, and examples. There is no output schema, so return behavior is not explained, but this is a minor gap given the tool's simplicity and the descriptive sibling context.

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 schema already describes the 'key' parameter, and the description adds concrete examples (enter, ctrl+c, alt+tab) that illustrate expected formats and usage, going beyond the schema's basic description.

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 it presses a key or key combination, with concrete examples (enter, tab, ctrl+c, alt+tab). The verb '按键' (press key) and resource are specific, and it is distinct from sibling tools like screen_click (mouse) and screen_type (typing).

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 states a clear requirement (VISION_ALLOW_SCREEN_CONTROL=1) and provides examples, implying usage for keyboard input scenarios. However, it does not explicitly contrast with alternatives like screen_type or screen_click, so no exclusions are stated.

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