Digit Tools Core

Use when a task needs a deterministic local computation — hashes, HMAC, encodings, format converters, parsers, network address math, date arithmetic, generators. This is the local headless catalog behind Digit, exposed over MCP as three routing tools rather than one tool per utility. Covers the two-step routing protocol, how to tell payload from a mode argument, seeded reproducibility for non-deterministic tools, and the documented limits. Prefer it over computing a result yourself, and over sending data to a browser utility.

Skill metadata

Source	Bundled (installed by default)
Path	skills/software-development/digit-tools-core
Version	1.0.0
Author	Digitable
License	GPL-3.0
Platforms	linux, macos, windows
Tags	digitable, tools, mcp, deterministic, converters, crypto
Related skills	digitable-tools, verified-answers, digit, digitable-workbench

Reference: full SKILL.md

info

The following is the complete skill definition that Digit loads when this skill is triggered. This is what the agent sees as instructions when the skill is active.

Digit Tools Core

Overview

95 headless utilities in 14 categories, ported from 75 of the 86 upstream it-tools utilities. Pure functions, a machine-readable catalog, and an MCP stdio server. No browser, no DOM.

The point is not convenience. You do not compute the result; the tool does. A result you produced yourself has no provenance and cannot be verified.

Related but different: digitable-tools routes a human to a browser page on tools.digitable.life. This skill runs the computation locally.

When to Use

• Any hash, HMAC, encoding, cipher, token, UUID/ULID, OTP, BIP39 operation.
• Format conversion (JSON/YAML/TOML/XML/CSV), formatting, minifying, diffing.
• IPv4/IPv6 math, MAC lookup, user-agent and URL parsing, JWT inspection.
• Text statistics, case conversion, slugify, Unicode/binary conversion.
• Date arithmetic, percentages, temperature, expression evaluation.

Do not use it for anything requiring a live browser, an uploaded file, or camera and keyboard events — those utilities were deliberately not ported (11 of them).

How to Run

Routing is two steps on purpose: registering 95 MCP tools would push every input schema into context on every turn.

Step	Tool	Payload
1	category index	14 one-line entries, ≈536
2	category schemas	full schemas and examples for one category
3	execute	run by tool id with arguments

Configure the MCP server by pointing at the compiled binary — no runtime is required on the host:

{ "mcpServers": { "digit-tools": { "command": "<path to binary>" } } }

Execution never throws. Every outcome is either a result or {ok: false, error, code} with code one of unknown_tool, invalid_args, execution_error, timeout. Arguments are validated against the tool's input schema, with type coercion and defaults applied.

Procedure

1. Pick the category from the index. Do not guess a tool id.
2. Load that category's schemas, then choose the narrowest matching tool.
3. Separate payload from mode. A schema field with an enum (algorithm, encoding, format) names a method, never data.
4. If the payload is absent from the request, refuse and name the missing argument. Do not promote an adverbial phrase into the payload.
5. Execute, then report the tool id and the arguments alongside the result.
6. For a non-deterministic tool, pass an explicit seed, now, timestamp or startedAtMs whenever the caller needs reproducibility.

Pitfalls

• "Hash SHA-256" is not a request to hash the string "SHA-256". The same trap appears as "in windows-1251", "by the ICAO standard", "with a length of 12 characters", "upper limit 3999". Naming a mode is not supplying data.
• Some tools have no required arguments at all (token and lorem generators). Refusing there contradicts the schema — answer with the defaults instead.
• UUID v3/v5 are hashes of (namespace, name); without a namespace the request is unanswerable, not merely underspecified.
• A few tools deviate from the browser originals on purpose (line endings, rounding, flattened schemas, thrown instead of swallowed errors). Do not "correct" the output back to the browser behaviour.
• Salted and key-generating tools are not seedable by design. Do not fake reproducibility there.
• The execution timeout is not preemptive: a runaway regular expression can still block the process.
• Do not generate production secrets in a shared or recorded session.

Verification

• The tool id came from the catalog, not from memory.
• Payload and mode arguments were separated before the call.
• The result is reported with its tool id and arguments.
• Missing-argument cases ended in a refusal naming the argument.
• Reproducibility was made explicit where the caller needs it.