io.github.daedalus/mcp-cryptography

by daedalus

Overview Schema Source Related Servers Discussions Admin

Python

Remote

aes_decrypt

Decrypt AES-encrypted data using hex-encoded key, ciphertext, and IV. Supports CBC and GCM modes.

Instructions

Decrypt AES ciphertext.

Args: key: Hex-encoded AES key. ciphertext: Hex-encoded ciphertext. iv: Hex-encoded initialization vector. mode: Encryption mode - 'CBC' or 'GCM' (default CBC).

Returns: Decrypted string.

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>",
      "ciphertext": "<ciphertext>",
      "iv": "<iv>"
    },
    "name": "aes_decrypt"
  }
}

Input Schema

Name	Required	Default
`iv`	Yes
`key`	Yes
`mode`	No	CBC
`ciphertext`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Jul 30, 2026

TDQS

A4.2/5.0

Behavior4/5

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

The description discloses that inputs must be hex-encoded, mode options, and that it raises ValueError for invalid key size, which is sufficient for a pure function with no side effects.

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-structured with Args, Returns, Raises sections, front-loaded with the main purpose, and every sentence provides value.

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?

Given the output schema exists and the description explains parameters, return value, and error condition, it is complete for a decryption tool.

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?

Schema coverage is 0%, so the description adds essential meaning: specifying hex-encoding, mode options, and default value, which the schema lacks.

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 'Decrypt AES ciphertext' with a specific verb and resource. It distinguishes from sibling tools like aes_encrypt and other decryption tools.

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?

The description does not provide guidance on when to use this tool vs alternatives, such as symmetric vs asymmetric decryption, or prerequisites like key generation.

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