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double_click_at

Double-clicks at viewport coordinates using trusted CDP events to enter edit mode in canvas editors, select words in contenteditable elements, or target coordinate-based controls.

Instructions

Double-click at specific viewport coordinates using CDP trusted events. Dispatches two rapid mousePressed/mouseReleased cycles with clickCount=2 on the second pair. Supports modifier keys. Coordinates are CSS pixels relative to the browser viewport. When to use: for entering edit mode in canvas-based editors (Excalidraw text boxes, Google Sheets cells), selecting words in contenteditable elements, or any double-click on coordinate-targeted elements. Related: click_at (single click at coordinates), double_click (double-click DOM elements by selector), insert_text (type text after entering edit mode via double-click). Multi-agent: agent-scoped tabs; cross-agent reject with TAB_NOT_OWNED; cap configurable (default 8, 1-64). Pass tab_id only when this agent owns multiple tabs; auto-resolves otherwise. RETURNS change_report: when this tool runs, the response includes a change_report field with a compact diff of what the action mutated (URL, dialogs_opened, nodes_added, nodes_removed, attrs_changed, inputs_changed, focus_shift). Use this to learn the consequence without calling read_page next. If the report exceeds the size cap, change_report.truncated:true and change_report_hint are set; call read_page for the full state.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
xYesX coordinate in viewport CSS pixels
yYesY coordinate in viewport CSS pixels
altNoHold Alt key during double-click
ctrlNoHold Ctrl key during double-click
shiftNoHold Shift key during double-click
clientYesAllowlisted client label. Validated against the shared v0.9.36 server/extension allowlist (see mcp/src/tools/visual-session.ts -- MCP_VISUAL_CLIENT_LABELS). Required.
tab_idNoOptional. Tab id this action targets. Omit when the calling agent owns exactly one tab; pass to disambiguate when the agent owns multiple. Single-tab agents and legacy popup/sidepanel/autopilot do not need to pass this.
is_finalNoWhen true, the visual session clears immediately after this tool resolves. Optional (default false).
visual_reasonYesShort human-readable reason shown in the overlay (for example, "Logging in to GitHub"). Required.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.8/5.0
Behavior5/5

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

No annotations are provided, so the description carries the full burden and does so well: it discloses CDP trusted events, the exact event sequence (two mousePressed/mouseReleased cycles, clickCount=2 on the second), modifier support, coordinate semantics, multi-agent tab ownership behavior with TAB_NOT_OWNED and a configurable cap (default 8, 1-64), and the change_report return including truncation handling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose, then usage, related tools, multi-agent notes, and return behavior in a logical order. Dense but nearly every sentence earns its place; the multi-agent and change_report paragraphs are long and slightly overlap with what the schema says about tab_id.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a coordinate-action tool with no output schema, the description is complete: it covers invocation semantics, coordinate system, modifiers, concurrency/ownership rules, and even describes the change_report payload and truncation escape hatch so the agent need not call read_page reflexively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% so the baseline is 3, but the description adds real meaning beyond the schema: it clarifies that coordinates are viewport-relative CSS pixels, that modifiers are applied during the double-click, and gives guidance on when to pass tab_id (only when the agent owns multiple tabs; auto-resolves otherwise).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Double-click at specific viewport coordinates') and immediately distinguishes itself from siblings by naming click_at (single click), double_click (DOM by selector), and insert_text. An agent can route correctly without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit 'When to use' section names concrete scenarios (Excalidraw text boxes, Google Sheets cells, contenteditable word selection) and a 'Related' section contrasts each alternative. When-to-use and alternatives are both spelled out.

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

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