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hydra_attack

Launch credential brute force attacks against network services using username and password lists to discover valid login credentials.

Instructions

Perform a credential brute force attack using Hydra.

WARNING: This is a destructive operation that may trigger account lockouts, IDS/IPS alerts, and log entries on the target system. Only use with explicit written authorization from the target system owner.

Args: target: Target IP or hostname. service: Service protocol to attack (e.g. "ssh", "ftp", "http-post-form"). userlist: Path to username list file. passlist: Path to password list file. port: Override default port for the service. threads: Number of parallel attack threads (default: 16, max: 64). stop_on_success: Stop after finding the first valid credential pair. timeout: Override scan timeout in seconds.

Returns: List of discovered valid credentials.

Note: - Requires explicit human authorization before execution. - Consider rate limiting to avoid lockouts. - Target must be in tengu.toml [targets].allowed_hosts.

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": {
      "target": "<target>",
      "service": "<service>",
      "userlist": "<userlist>",
      "passlist": "<passlist>"
    },
    "name": "hydra_attack"
  }
}

Input Schema

Name	Required	Description	Default
`port`	No
`target`	Yes
`service`	Yes
`threads`	No
`timeout`	No
`passlist`	Yes
`userlist`	Yes
`stop_on_success`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.1Aug 2, 2026

TDQS

A4.8/5.0

Behavior5/5

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

The description is highly transparent about behavioral consequences: it warns of account lockouts, IDS/IPS alerts, log entries, and the need for authorization. Since there are no annotations, this description fully carries the burden of disclosing the destructive nature of the operation, going beyond simple 'mutating' labels.

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 well-organized into warning, args, returns, and notes. It is a bit long but every sentence adds necessary safety or usage context. It is front-loaded with the core action and warning, making it efficient.

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 an attack tool with 8 parameters and no annotations, the description is robust: it covers purpose, all parameter meanings, output (list of discovered credentials), and critical prerequisites (authorization, allowed host). This is sufficient for an agent to invoke it correctly, and the note about rate limiting adds responsible usage guidance.

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

Parameters5/5

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

The 'Args' section provides a one-line explanation for each of the 8 parameters, including defaults and limits (e.g., 'threads' default 16, max 64). This meaningfully supplements the input schema, which only lists names and types, giving the agent guidance on how to set each parameter.

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 a clear verb-object directive: 'Perform a credential brute force attack using Hydra.' It names the specific tool and attack type, distinguishing it from other scanning/attack tools in the sibling list. This establishes a precise purpose.

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?

It provides explicit authorization requirements and warnings about destructive impact ('Only use with explicit written authorization', 'Requires explicit human authorization before execution'). It also notes the target must be in an allowed_hosts list, giving clear invocation constraints. However, it does not name alternative tools for when not to use it, so it stops short of a 5.

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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