Scroll an Android screen by dragging up to see below, down to see above, or left/right to change pages; distance sets gesture length as a screen fraction.
Scroll by swiping: 'up' shows what is below, 'down' what is above, 'left' and 'right' move between pages. distance is a fraction of the screen.
| Name | Required | Description | Default |
|---|---|---|---|
| serial | No | ||
| distance | No | ||
| direction | No | up |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.1.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral semantics (direction-to-scroll mapping, distance as a fraction of screen), but says nothing about side effects, whether the gesture can trigger navigation/activation, or device/serial targeting 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?
A single sentence that is front-loaded with the action and then packs the direction semantics and distance units into the same breath. Every clause earns its place; nothing is redundant.
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?
An output schema exists, so return values need not be described, and annotations cover the safety profile. The remaining gap is the unexplained serial parameter; otherwise the description is sufficient to invoke this simple gesture tool correctly.
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 coverage is 0%, so the description must carry the load. It does explain direction (all four values) and distance ('a fraction of the screen'), which is meaningful compensation, but the serial parameter — how to target a specific device — is left completely undocumented in both schema and 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?
States a specific verb+resource ('scroll by swiping') and immediately resolves the ambiguity in the direction values by mapping each to its scroll effect. It is clearly distinct from the sibling set (tap, tap_element, type_text, press_key), though it does not explicitly name an alternative gesture tool.
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?
Usage is only implied: the reader infers 'use this to scroll/gesture-navigate.' There is no explicit when-to-use, when-not-to-use, or pointer to a sibling (e.g., tap_element for clicking a target), so the agent must infer the context itself.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.