darknet-mcp-server

breachPassword

Verify if a password has appeared in known data breaches using the Pwned Passwords k-anonymity API. Only the first 5 characters of the SHA-1 hash are sent, preserving privacy.

Instructions

Check if a password has appeared in known data breaches using the Pwned Passwords k-anonymity API. Only the first 5 characters of the SHA-1 hash are sent to the server. Free, no API key required.

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": {
      "password": "<password>"
    },
    "name": "breachPassword"
  }
}

Input Schema

Name	Required	Description	Default
`password`	Yes	The password to check

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 23, 2026

TDQS

A4.6/5.0

Behavior5/5

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

No annotations are provided, so the description fully carries the behavioral disclosure burden. It reveals key traits: only the first 5 characters of the SHA-1 hash are sent, the service is free, and no API key is needed. This is significant and goes beyond a simple 'check' statement.

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 concise sentences: first states purpose, second adds relevant technical and access details. No fluff or redundancy; every word earns its place.

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

Completeness4/5

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

The tool is simple (one parameter, no output schema), and the description covers purpose, method, privacy, and requirements. It does not describe the response format, but for this low-complexity tool with no output schema, the absence is a minor gap rather than a critical omission.

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 already fully describes the 'password' parameter, so baseline is 3. The description adds meaningful context about how the password is processed (hashed and truncated), which enriches the parameter semantics beyond the schema.

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 clearly states the tool checks if a password appears in known data breaches via the Pwned Passwords API. It is specific about the operation and distinguishes itself from sibling tools like breachList or breachGet, which focus on breach datasets rather than direct password verification.

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

Usage Guidelines4/5

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

The description implies usage: checking a password against breach data. It provides clear context (k-anonymity, no API key required) but does not explicitly mention when not to use it or recommend alternatives. This fits 'clear context, no exclusions'.

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

Deploy Server