snapdiff-mcp

snapdiff_capture_screenshot

Take a screenshot of a web page to inspect layout, verify rendering, or capture a baseline for visual comparison. Supports full page, specific elements, dark mode, and custom viewport.

Instructions

Take a screenshot of a web page. Use this when you need to see what a webpage looks like right now — to inspect layout, verify rendering, or capture a baseline for later comparison.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "url": "<url>"
    },
    "name": "snapdiff_capture_screenshot"
  }
}

Input Schema

Name	Required	Description
`url`	Yes	The full URL to screenshot
`full_page`	No	Capture the entire scrollable page. Default false
`dark_mode`	No	Force dark color scheme. Default false
`selector`	No	CSS selector to capture only a specific element
`width`	No	Viewport width in pixels. Default 1280

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.4.2Jun 17, 2026

TDQS

A3.5/5.0

Behavior3/5

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

No annotations are provided, so the description must disclose behavioral traits. It states 'Take a screenshot' which implies read-only, but does not elaborate on side effects, permissions, rate limits, or response format. For a simple screenshot operation, this is minimally acceptable but lacks depth.

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?

Two sentences, zero wasted words. First sentence states the action. Second sentence lists use cases. Information is front-loaded and efficient.

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

Completeness3/5

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

The description covers the basic purpose and usage context. However, given the presence of sibling tools with overlapping purposes, it does not hint at when to choose this tool over alternatives. No information about return values or output, which might be inferred but is not explicit.

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

Parameters3/5

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

Schema description coverage is 100%, so baseline is 3. The description adds no parameter-specific information beyond the schema; it merely states the overall action. No extra semantics are provided.

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

Purpose4/5

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

Description clearly states tool takes a screenshot of a web page and lists use cases (inspect layout, verify rendering, capture baseline). It partially distinguishes from sibling 'snapdiff_capture_baseline' by emphasizing current state, but the phrase 'capture a baseline for later comparison' overlaps with that sibling's likely purpose, preventing a 5.

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

Usage Guidelines3/5

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

Provides a clear when-to-use context: 'when you need to see what a webpage looks like right now.' However, it does not mention when not to use this tool (e.g., for baseline comparison or verification) nor direct users to alternatives among siblings, leaving the agent without explicit guidance.

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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