diff_screenshots

SERVERNodebench SOURCEnodebench-mcp

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-homenshum-nodebench/diff-screenshots.md

WHAT IT DOES

What diff_screenshots does on Nodebench

AI agents call diff_screenshots to retrieve information from Nodebench without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why diff_screenshots is rated Low

This tool retrieves and analyzes data (pixel-level comparison of two images) without creating, modifying, deleting, or executing operations. It generates computed outputs (perceptual similarity metrics, difference regions, visual summary) based on input images. The stated use cases (visual regression testing, UI QA, screenshot comparison) are all observational. No side effects occur beyond the analysis itself.

From the tool's definition Tool 'diff_screenshots' performs image comparison and analysis: 'Compare two images structurally using pixel-level analysis.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs diff_screenshots safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Nodebench, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For diff_screenshots, this is the rule to start with:

diff_screenshots Allowed

diff_screenshots is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "diff_screenshots": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Nodebench, apply this rule, and every diff_screenshots call is checked against it from then on.

FAQ

Questions about diff_screenshots

What does the diff_screenshots tool do? +

Compare two images structurally using pixel-level analysis. Computes perceptual similarity, difference regions, and visual summary. Requires sharp. Useful for visual regression testing, UI QA, and screenshot comparison. It is categorised as a Read tool in the Nodebench MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on diff_screenshots? +

Register the Nodebench MCP server in PolicyLayer and add a rule for diff_screenshots: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Nodebench. Nothing to install.

What risk level is diff_screenshots? +

diff_screenshots is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit diff_screenshots? +

Yes. Add a rate_limit block to the diff_screenshots rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block diff_screenshots completely? +

Set action: deny in the PolicyLayer policy for diff_screenshots. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides diff_screenshots? +

diff_screenshots is provided by the Nodebench MCP server (nodebench-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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