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wwebjs-mcp

wwebjs-mcp

by victor-halla
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

session_getPageScreenshot

Capture a screenshot of the WhatsApp Web page for a given session ID to inspect the current interface state.

Instructions

[Session] Get page screenshot. Screenshot of the client with the given session ID.

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": {
      "sessionId": "<sessionId>"
    },
    "name": "session_getPageScreenshot"
  }
}

Input Schema

NameRequiredDescriptionDefault
sessionIdYesUnique identifier for the session (alphanumeric and - allowed)

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, and the description does not disclose the return format (e.g., image data, base64), error conditions, or any side effects. It only restates the basic function without adding behavioral detail.

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?

The description is short and front-loaded with the action. The second sentence repeats the first idea, slightly redundant, but overall efficient and to the point.

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

Completeness2/5

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

There is no output schema, so the description should explain what the screenshot returns or any requirements. It does not. Given the lack of annotations and output schema, the description is incomplete for a tool that produces a screenshot.

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 coverage is 100%—the sessionId is clearly described with example and format. The description adds no additional meaning beyond what the schema already provides, so baseline 3 is appropriate.

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?

The description clearly states it fetches a page screenshot for a given session, using a specific verb and resource. It is distinguishable from sibling session tools like session_getSessions which list sessions or session_qr which gets QR codes.

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

Usage Guidelines2/5

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

No guidance on when to use this tool vs alternatives, no mention of prerequisites like an active session, and no mention of where the screenshot comes from or what to do with it.

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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