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click_at

Click at exact viewport coordinates with trusted browser events for canvas, SVG, overlays, or elements where DOM-based clicks fail. Supports shift, ctrl, and alt modifiers.

Instructions

Click at specific viewport coordinates using CDP trusted events. Supports modifier keys for shift+click (multi-select), ctrl+click, alt+click. Coordinates are CSS pixels relative to the browser viewport (use getBoundingClientRect() values). Returns success/failure with method used. When to use: for canvas elements, SVG graphics, overlays, or any element where DOM-based click (click tool) does not work. Fallback for click failures. Related: click (preferred for DOM elements -- use click_at only when click fails), get_dom_snapshot (check element coordinates via position data), drag (for click-and-drag interactions). 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 click
ctrlNoHold Ctrl key during click
shiftNoHold Shift key during click (for multi-select)
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 exist, so the description carries full behavioral burden and does so: CDP trusted events, multi-agent tab ownership with TAB_NOT_OWNED rejection, a configurable concurrency cap (default 8, 1-64), tab_id auto-resolution semantics, and a detailed change_report return contract 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?

Long but front-loaded and sectioned (purpose, when-to-use, related, multi-agent, returns), with each block serving a distinct decision. It is verbose in places—the change_report paragraph could be tighter—but almost nothing is pure filler for a tool with this much surface area.

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?

Despite no output schema, the description explains the return value (change_report fields, truncation flag, read_page fallback) and covers multi-agent ownership and tab targeting. Nothing an agent needs to invoke it correctly is missing.

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 meaning beyond it: shift+click is explained as multi-select, coordinates are pinned to CSS pixels relative to the viewport with getBoundingClientRect() as the source, and tab_id's omit-vs-pass behavior is spelled out.

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 ('Click at specific viewport coordinates using CDP trusted events') and immediately scopes it against the sibling click tool. An agent can distinguish it from click, double_click_at, and drag 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' clause names the target cases (canvas, SVG, overlays) and positions it as a fallback for click failures. The 'Related' section names the preferred alternative (click) and the exact condition for switching ('use click_at only when click fails'), plus get_dom_snapshot and drag.

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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