io.github.daedalus/mcp-cryptography

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hash_sha256

Compute SHA-256 hash of a string or base64-encoded bytes, returning a hexadecimal digest for data integrity verification.

Instructions

Compute SHA-256 hash.

Args: data: String or base64-encoded bytes to hash.

Returns: Hex-encoded hash.

Example: >>> hash_sha256("Hello, World!") 'dffd6021bb2bd5b0af676290809ec3a53191dd81c7f70a4b28688a362182986f'

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": {
      "data": "<data>"
    },
    "name": "hash_sha256"
  }
}

Input Schema

Name	Required	Description	Default
`data`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Jul 30, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations provided, the description carries the full burden. It clearly states input format (string or base64-encoded bytes) and output format (hex-encoded hash). It does not disclose error behavior or side effects, but for a pure hash function, the transparency is sufficient and adds value beyond what schema alone provides.

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 extremely concise, using just four lines: purpose, Args, Returns, and Example. It is front-loaded with the core action, and every sentence adds necessary information without redundancy.

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 low complexity (one parameter, simple output) and the presence of an output schema, the description covers the essentials. It explains input and output, provides an example, and defines the behavior. Minor omission: no mention of it being a pure function or idempotent, but 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 must compensate. It explains the 'data' parameter as 'String or base64-encoded bytes to hash,' which adds semantic meaning. The return value and example further clarify usage. This adequately fills the gap left by 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 explicitly states 'Compute SHA-256 hash,' clearly identifying the verb (compute) and resource (SHA-256 hash). Among sibling tools like hash_sha512 and hash_sha1, the name and description distinguish this tool by specifying the algorithm.

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 on when to use SHA-256 versus other hash algorithms (e.g., SHA-512 or SHA-1). The description does not provide any context for selection or alternatives, relying solely on the tool name and sibling list for differentiation.

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