Hopi

Hash generator

hopi_hash_generator

Read-onlyIdempotent

Compute the SHA-256, SHA-1 or SHA-512 hash of a piece of text and return the hex digest. Uses WebCrypto on Hopi's server. SHA-1 is included for compatibility with older systems only and should not be used for anything new. Source: https://hopi.co.uk/hash-generator/

Input Schema

TableJSON Schema

Name	Required	Description	Default
`text`	Yes	The text to hash
`algorithm`	No	Hash algorithm (default SHA-256)	SHA-256

Output Schema

TableJSON Schema

Name	Required	Description
`hex`	No
`bits`	No
`summary`	Yes
`algorithm`	No
`source_url`	Yes	The tool's page on hopi.co.uk (cite or open to check the figure)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026
- addedOutput schema / required
```
Added value: +[
+  "source_url",
+  "summary"
+]
```
First observedSep 20, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds meaningful context by stating that hashing happens using WebCrypto 'on Hopi's server', implying the input text is transmitted to the server, and optionally provides a source link.

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?

Three short sentences with the core operation front-loaded. The SHA-1 warning and source link add context without adding bloat, and no sentence is redundant.

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?

The output schema covers return value details; annotations cover side-effect safety; and the description covers input, algorithm options, compatibility concerns, and server-side execution. Nothing an agent needs to invoke the tool correctly is missing.

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 coverage is 100%, so the baseline is 3. The description adds value by explaining the supported algorithms and explicitly warning that SHA-1 is legacy-only, which helps the agent make a correct algorithm choice.

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?

States a specific action ('Compute') with a clear resource ('hash of a piece of text') and enumerates the exact algorithms and output form ('hex digest'). This clearly differentiates it from siblings such as hopi_hash_identifier, which performs a different task.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use the tool (when a text hash is needed) but does not name alternative tools or state when not to use it. It does provide useful algorithm-level guidance: SHA-1 is for compatibility only and should not be used for new work.

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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