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Capture current viewport

browser_screenshot
Read-only

Captures the visible browser viewport as a 1280x800 PNG for the active or specified session. Use it to inspect the current screen, and choose multi-viewport capture for coverage beyond the visible area.

Instructions

Captures one 1280x800 PNG of the current viewport without navigation or scroll changes. Use this for the visible region; use browser_snapshot_layers for multi-viewport coverage. An omitted session_id targets the active/default session. Returns one layer with its offset, dimensions, and base64 PNG data.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
session_idNoOptional browser tab/session identifier.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.3.5
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "type": "object"
+}
  2. First observedv1.3.2

TDQS

A4.7/5.0
Behavior4/5

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

Annotations already mark this as read-only and non-destructive, and the description adds useful behavioral guarantees: no navigation/scroll side effects, a fixed 1280x800 image, and a single-layer return value. It does not cover things like rate limits, but those are not material here.

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

Conciseness5/5

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

Three sentences with no filler; the primary behavior and key limitation are front-loaded, the sibling comparison follows, and the default-parameter behavior closes the only remaining ambiguity.

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?

With only one optional parameter, an output schema present, and annotations describing safety, the description covers all necessary selection and invocation guidance. The agent knows exactly what will happen, what it will get back, and which tool to choose instead for broader coverage.

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?

The schema fully documents session_id as an optional identifier, and the description adds the important default behavior (omitted session_id targets the active/default session). This exceeds the baseline because it resolves the main semantic question an agent would have.

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?

The description states a precise action ('Captures one 1280x800 PNG'), a specific resource ('current viewport'), and an explicit constraint ('without navigation or scroll changes'). It also distinguishes itself from the sibling browser_snapshot_layers, so an agent can identify the correct tool immediately.

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?

It explicitly says to use this for the visible region and to use browser_snapshot_layers for multi-viewport coverage, and it clarifies the default behavior when session_id is omitted. This gives clear selection criteria without leaving alternatives to inference.

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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