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

No annotations are provided, so the description carries the full behavioral burden. It discloses a meaningful behavior: automatic video-coordinate-space handling, which removes math from the caller. However, it does not mention side effects, gesture semantics (fling vs. smooth scroll), or completion behavior—reasonable for a simple action but not comprehensive.

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?

Two short sentences with no filler. The primary action is front-loaded, and the coordinate-space differentiator is stated efficiently. Every sentence contributes to selecting and invoking the tool.

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 three-parameter, no-output-schema tool, the definition is nearly complete. Required parameters are clear, the default behavior is sensible, and the coordinate-space hint removes a common ambiguity. It only lacks explicit routing against sibling gesture tools, which is handled under usage guidelines.

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 input schema has 100% description coverage for all three parameters, so the baseline applies. The description does not add parameter-level detail beyond the schema, though the coordinate-space note helps agents understand why they should not compute coordinates manually.

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 states a specific action and resource: 'Scroll the screen in a direction on an Android device.' It clearly identifies the behavior and platform. It does not explicitly differentiate from sibling gesture tools like device_swipe or device_scroll_to_element, but the direction-based scroll intent is clear.

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 phrase 'Uses video coordinate space automatically. No coordinate math needed.' provides practical context for when to choose this tool over coordinate-based gesture tools. It stops short of naming alternatives or explicit when-not-to-use conditions, but the guidance is directionally useful.

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