VOICE.md

A format specification for describing a brand's communicational identity to AI agents. VOICE.md gives agents a persistent, structured understanding of how a brand speaks — its lexicon, tone, beliefs, audiences, and per-surface constraints — and a linter that validates both the spec and the strings agents produce against it.

VOICE.md is to copy and tone what DESIGN.md is to visual identity.

Why this exists

Coding agents now have AGENTS.md for repository conventions and DESIGN.md for visual systems. Content has nothing comparable. Brand voice lives in PDFs and Notion pages that humans read but agents can't validate against, so every LLM that produces copy for a brand — Verk Agent generating posts, Claude Code writing UI strings, Cursor producing email templates — relies on whatever voice context happens to be inlined into the current prompt. The result is drift across surfaces and across runs.

VOICE.md fixes this by being a single, versionable, lint-able source of truth that an agent reads once at session start and that CI can verify against every PR.

The Format

A VOICE.md file combines machine-readable voice tokens (YAML front matter) with human-readable rationale (markdown prose). Tokens give agents exact values. Prose tells them why those values exist and how to apply them.

---
name: Efeonce Group
language:
  primary: es-419
  treatment: tu
personality:
  traits:
    - architect-hands-dirty
    - uncomfortable-honesty
    - proof-obsession
beliefs:
  - id: vanity-metrics-pact
    statement: Las vanity metrics son un acuerdo de silencio entre agencia y cliente.
lexicon:
  protected_terms:
    - term: "Loop Marketing"
      never: ["loop marketing", "LM", "el Loop"]
  forbidden:
    - phrase: "soluciones integrales"
      reason: jerga-agencia-genérica
audiences:
  - id: strategic-executive
    name: Estratégico-Ejecutivo
    is_default: true
surfaces:
  - id: email-subject
    max_length: 50
    unit: characters
    forbid_emoji: true
---

## Overview

Efeonce sounds like a director of strategy who built the system they operate.
...

An agent that reads this file knows exactly how to write an email subject for Efeonce, what phrases to avoid, what terminology to protect, and which audience to address by default.

Getting Started

Validate a VOICE.md against the spec — catch broken references, missing defaults, forbidden phrases, and structural issues — as structured JSON that agents can act on.

npx @efeonce/voice.md lint VOICE.md

{
  "findings": [
    {
      "severity": "error",
      "path": "lexicon.forbidden:soluciones integrales",
      "rule": "forbidden-term-used",
      "message": "Forbidden phrase \"soluciones integrales\" used. Reason: jerga-agencia-genérica."
    }
  ],
  "summary": { "errors": 1, "warnings": 0, "info": 0 }
}

Validate a target string against a specific surface — this is what CI hooks into:

npx @efeonce/voice.md lint-string VOICE.md email-subject "Potenciar tu negocio 🚀"

{
  "findings": [
    { "rule": "forbidden-term-used", "message": "Forbidden phrase \"potenciar\" used." },
    { "rule": "emoji-forbidden-here", "message": "Surface \"email-subject\" forbids emoji." }
  ],
  "summary": { "errors": 2 }
}

Compare two versions to detect regressions:

npx @efeonce/voice.md diff VOICE.md VOICE-v2.md

Exits with code 1 if the new version has more errors or warnings than the old — plug it into CI.

Exporting

VOICE.md becomes useful when other systems consume it.

# Inject this block as a system prompt for your content agents
npx @efeonce/voice.md export --format prompt VOICE.md > voice-prompt.md

# Generate an ESLint config that fails build on forbidden phrases in JSX strings
npx @efeonce/voice.md export --format eslint-config VOICE.md > .eslintrc.voice.cjs

# Flat JSON for i18n linters or custom tooling
npx @efeonce/voice.md export --format json VOICE.md > voice.json

Spec

The full VOICE.md specification lives at docs/spec.md. The full rules table lives at docs/rules.md.

Output the spec for injection into agent prompts:

npx @efeonce/voice.md spec
npx @efeonce/voice.md spec --rules
npx @efeonce/voice.md spec --rules-only

Token Schema (condensed)

Section	Purpose
language	Locale, treatment (tu/usted/you/etc), contractions
personality	Archetypes and named traits
register	Default formality, emoji policy, punctuation rules
beliefs[]	Inheritable narrative DNA — every piece must trace to at least one
lexicon.protected_terms[]	Canonical names with their forbidden variations
lexicon.forbidden[]	Phrases that dilute voice, with reasons
lexicon.reserved_motifs[]	Editorial devices owned by sub-voices
audiences[]	Registers per buyer persona, with one is_default
surfaces[]	Per-channel constraints: length, case, structure
tones[]	Modulation patterns (explain, condense, provoke, instruct, demonstrate)
units[]	Sub-brands with personality emphasis on parent traits
formatting	Capitalization, numbers, emphasis, currency
components	Templated piece types (pitch document, client report, etc.)

See examples/VOICE.md for a complete production-grade file — the actual VOICE.md used by Efeonce Group across Greenhouse, Kortex, Verk, and Efeonce Web.

Status

VOICE.md is at version alpha. The spec, token schema, and CLI are under active development. Expect changes as the format matures.

License

Apache 2.0. Contributions welcome.

Why Apache 2.0?

Same license as DESIGN.md and AGENTS.md. Maximizes adoption in enterprise contexts and removes friction for derivative tooling.

Authors

Created and maintained by Efeonce Group SpA, an ASaaS (Agency-as-a-Service) operating in Chile, Colombia, México, and Perú.