facebook-web-mcp

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Check Facebook session

check_facebook_session

Read-only

Check if the persistent browser profile is logged into Facebook. Launches the browser on first use and reports any security challenges without answering them, leaving them for the user.

Instructions

Report whether the persistent browser profile is logged into Facebook. Launches the browser on first use. Never logs in, and never answers a security challenge — if one is present it says so and leaves the window open for the user to handle. Run this before anything else in a session.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "check_facebook_session"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 1, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Even though annotations already declare readOnlyHint=true and openWorldHint=true, the description adds valuable behavioral details: it launches the browser on first use, never interacts with login flows, and if a security challenge appears, it reports it and leaves the window open for the user. This goes well beyond the structured annotations.

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?

The description is three sentences, front-loaded with the primary purpose. Every sentence adds distinct value: what it reports, side effects (browser launch), and boundaries (never logs in/challenge handling) plus the explicit usage directive. No wasted words.

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?

For a zero-parameter, no-output-schema check tool, the description covers all necessary context: the exact question it answers, its side effects, its non-actions, and when to run it. There is no ambiguity; an agent can correctly invoke it without further information.

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 tool has zero parameters, so the schema is trivially 100% covered. Per the rubric, 0 params yields a baseline of 4. The description adds no parameter-specific meaning, but none is needed.

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 opens with 'Report whether the persistent browser profile is logged into Facebook,' a specific verb ('Report') and resource ('persistent browser profile') that clearly states the tool's function. It is also distinguished from siblings like 'open_facebook_login' by explicitly stating it never logs in.

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?

The description gives explicit when-to-use guidance: 'Run this before anything else in a session.' It also provides when-not-to-use context by stating it never logs in and never answers security challenges, implying that other tools (e.g., open_facebook_login) are needed for those actions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.