HALO (GEMMA-by-GOOGLE)

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run_john

Crack password hashes with John the Ripper by providing a hash file and optionally specifying the hash format and wordlist path.

Instructions

Crack password hashes with John the Ripper against a wordlist.

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": {
      "hash_file": "<hash_file>"
    },
    "name": "run_john"
  }
}

Input Schema

Name	Required	Description	Default
`format`	No	Force a hash format.
`wordlist`	No	Wordlist path.	/usr/share/seclists/Passwords/Common-Credentials/darkweb2017_top-1000.txt
`hash_file`	Yes	Path to the hash file.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jul 10, 2026

TDQS

C2.9/5.0

Behavior2/5

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

With no annotations, the description should disclose behavioral traits. It only states the basic action without mentioning potential side effects (e.g., system resource usage), output location, error conditions, or required permissions. Important for a security tool that may be destructive.

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 a single succinct sentence that conveys the core purpose without extraneous information. It is well-structured and front-loaded, though it could include more detail without becoming verbose.

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?

Given no output schema, no annotations, and three parameters, the description is insufficient. It does not explain what happens after cracking (success output, logging), potential hash format constraints, or the role of the default wordlist. A more complete description would improve usability.

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 description coverage is 100%, so the baseline is 3. The description adds no additional meaning beyond what the schema already provides for each parameter (format, wordlist, hash_file). It does not clarify expected formats or relationships between parameters.

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 the tool cracks password hashes with John the Ripper using a wordlist, providing a specific verb and resource. However, it does not differentiate from sibling tools like run_hydra or run_ncrack that also perform password cracking.

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 is given on when to use this tool versus alternatives such as run_hydra (online brute-force) or run_searchsploit (exploit search). The description lacks any context about appropriate use cases or prerequisites.

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