io.github.daedalus/mcp-cryptography

by daedalus

Overview Schema Source Related Servers Discussions Admin

Python

Remote

aes_encrypt

Encrypt text with AES using a hex-encoded key, supporting CBC and GCM modes for data protection.

Instructions

Encrypt data using AES.

Args: key: Hex-encoded AES key (16, 24, or 32 bytes). data: String to encrypt. mode: Encryption mode - 'CBC' or 'GCM' (default CBC).

Returns: Dictionary with 'ciphertext' (hex) and 'iv' (hex).

Raises: ValueError: If key size is invalid.

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": {
      "key": "<key>",
      "data": "<data>"
    },
    "name": "aes_encrypt"
  }
}

Input Schema

Name	Required	Default
`key`	Yes
`data`	Yes
`mode`	No	CBC

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Jul 30, 2026

TDQS

A3.9/5.0

Behavior4/5

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

With no annotations, the description carries full burden. It discloses key requirements (hex-encoded, specific lengths), mode options (CBC/GCM), return format (ciphertext and iv as hex), and error behavior (ValueError for invalid key size). It is transparent about the operation and constraints.

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 structured as a docstring with Args, Returns, Raises sections. It is appropriately concise—every sentence adds value—though not the absolute minimum. It is easy for an AI agent to parse.

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?

Given the tool's moderate complexity (3 params, no output schema but described), the description is complete. It covers input requirements, mode options, return values, and possible errors. Minor missing details like padding scheme or IV generation are not critical.

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?

Schema description coverage is 0%, so the description adds vital meaning: key is hex-encoded AES key of 16/24/32 bytes, data is string to encrypt, mode is 'CBC' or 'GCM' with default. This compensates for the empty schema properties.

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 explicitly states 'Encrypt data using AES.' This clearly identifies the action (encrypt) and the resource/algorithm (AES). It distinguishes from sibling tools like aes_decrypt and other encryption algorithms.

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 provided on when to use this tool versus alternatives such as rsa_encrypt or fernet_encrypt. The description does not include any 'when to use' or 'when not to use' context, which is needed given the many sibling encryption tools.

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