Press and hold the left mouse button from (x1, y1) to (x2, y2) to select text, move items, or resize elements in background apps without moving the cursor or stealing focus.
Drag with the left mouse button from (x1, y1) to (x2, y2): select text, move items, resize.
| Name | Required | Description | Default |
|---|---|---|---|
| x1 | Yes | ||
| x2 | Yes | ||
| y1 | Yes | ||
| y2 | Yes |
Changes observed during successful MCP inspections.
v0.4.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and non-idempotent/non-readOnly, so the safety profile is covered. The description adds genuinely new behavioral detail by specifying the left mouse button, which is not in the annotations. It does not disclose the coordinate frame (screen vs. window), whether intermediate move events are emitted, or any focus/activation requirement — significant gaps for a drag gesture.
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?
One sentence, front-loaded with the action and gesture, followed by the parameter mapping and outcomes. No filler or repetition of the tool name.
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?
With no output schema, 0% parameter coverage, and a destructive mutation, the description is missing the essentials an agent needs to call it reliably: coordinate origin/units, whether the target window must be activated first, and what the tool returns or how failure is signaled. The use-case list is helpful but not sufficient.
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 0%, so the description must carry parameter meaning, and it partially does: 'from (x1, y1) to (x2, y2)' establishes that the first pair is the start point and the second pair is the drop point. It still leaves the coordinate origin and units unspecified, so it does not fully compensate for the schema gap.
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 (drag) plus the resource and gesture (left mouse button from (x1,y1) to (x2,y2)), and enumerates intended outcomes (select text, move items, resize). It is clearly distinguishable from click/scroll/type siblings by naming the press-drag-release movement. It stops short of explicitly contrasting itself with click, but the gesture is unambiguous.
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 three example outcomes (select text, move items, resize) imply when the tool applies, which is better than nothing. However, there is no explicit when-not guidance (e.g., use click for a single point, click_element for known targets) and no prerequisites such as needing the target window focused before dragging.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.