Lettr Skills

Agent skills for working with Lettr in code — installing the SDK, sending transactional email, authoring templates, managing audience and campaigns, wiring webhooks, and diagnosing delivery problems.

Works with Claude Code, Cursor, Codex, Windsurf, and other AI coding agents, across 6 official SDKs (PHP, Node, Python, Go, Rust, Java) plus the Laravel framework integration.

Available skills

Skill	Use when
install	Adding Lettr to a project: detect stack, install SDK, configure key, verify a sending domain.
sending	Send transactional email — HTML/text/template, attachments, tracking, batch, scheduling.
templates	Author Lettr-managed templates and validate merge tags.
audience	Lists, contacts (double opt-in, bulk), topics, properties, segments.
campaigns	Send, schedule, and report on dashboard-authored campaigns.
webhooks	Register endpoints and write the event handler.
diagnose	Triage delivery problems — bounces, unverified domains, silent webhooks, rate limits.

Each skill is a small, hand-written judgment layer. The exact SDK code and API details it points at live in _generated/ and are built from the Lettr docs.

Installation (end users)

npx skills add lettr-com/lettr-skills

Prerequisites

• A Lettr account and an API key from app.lettr.com/settings/api-keys, set as LETTR_API_KEY (keys start with lttr_).
• A verified sending domain in app.lettr.com/domains. The install skill walks through this.

Pair with the Lettr MCP server (optional)

The Lettr MCP server gives agents direct API access. These skills work with or without it.

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For maintainers

The per-language SDK references and the API catalog under _generated/ are generated, not hand-written — they're distilled from the docs and SDK repos that already exist as siblings of this repo:

../lettr-docs/quickstart/<lang>/*.mdx   →  _generated/sdk/<lang>/<topic>.md
../lettr-docs/openapi.json              →  _generated/api/index.md  (+ bundled openapi.json)

Workflow

You edit the upstream docs/SDK (which you already maintain), then:

npm run sync         # regenerate _generated/ from ../lettr-docs
npm run sync:check   # CI-friendly: exits 1 (and names stale files) if out of date

Commit the regenerated _generated/ along with your change. The committed output is what end users get — they don't have the source repos.

• Sources are declared in scripts/sources.json (languages, topics, paths).
• Generation logic is scripts/sync.mjs — strips Mintlify components from the docs and condenses the OpenAPI spec.
• CI (.github/workflows/sync-check.yml) runs sync:check against a fresh checkout of lettr-docs so drift can't be merged.

Never hand-edit anything under _generated/ — it's overwritten on the next sync. To change that content, change the upstream source and re-run sync.

License

MIT