Sendmux

Sendmux Agent Skills

Official Sendmux skills for AI coding agents.

Marketplace install

Claude and Codex users can install Sendmux as a plugin marketplace from this repository.

Claude app, Claude Desktop, and Cowork:

1. Open Customize.
2. Go to Plugins.
3. In Personal plugins, click + and choose Add marketplace.
4. Choose Add from a repository.
5. Enter Sendmux/skills, then install the Sendmux plugin.

Claude Code:

/plugin marketplace add Sendmux/skills
/plugin install sendmux@sendmux
/reload-plugins

Codex app and Codex CLI:

codex plugin marketplace add Sendmux/skills

Then open Plugins in the Codex app or /plugins in Codex CLI and install Sendmux from the Sendmux marketplace.

Direct Agent Skills install

Use skills add when your agent supports raw Agent Skills rather than plugin marketplaces.

npx skills add Sendmux/skills

Install one skill from the pack:

npx skills add Sendmux/skills --skill sendmux-send-email

Update an installed pack:

npx skills update

What This Pack Teaches

• Choose the cheapest correct Sendmux surface for the task: MCP for connected agents, the sendmux CLI for terminal one-shots, and SDKs for application flows.
• Use the right credential for each job: smx_root_* for account-level work, send-capable smx_mbx_* keys or owner-approved Sending-resource smx_agent_* tokens for sending, smx_mbx_* keys for single-mailbox work, and scoped smx_agent_* tokens for self-registered agent mailbox work.
• Prefer efficient calls: batch operations, cursor pagination, conditional requests, idempotency keys, counts, snippets, and delta sync where the public surface supports them.
• Verify results before reporting success.

Skills Catalogue

The catalogue is built item by item from the local API, SDK, CLI, and MCP source of truth.

Skill	Use when
sendmux-getting-started	Choosing a Sendmux surface, setting up auth, or making a first verified call.
sendmux-send-email	Sending single or batch transactional email.
sendmux-attachments	Uploading, downloading, or sending attachments without wasting context on base64.
sendmux-mailbox-agent	Reading, triaging, replying, or syncing one mailbox.
sendmux-management	Managing domains, mailboxes, sending accounts, webhooks, billing, and logs.
sendmux-cli	Using the sendmux CLI from a terminal.
sendmux-mcp-setup	Connecting Sendmux MCP servers to an agent client.
sendmux-token-efficient-usage	Choosing low-token Sendmux calls and avoiding wasteful reads.
sendmux-email-for-agents	Giving an AI agent an inbox, challenge-first self-registration flow, or email workflow, even when Sendmux is not named.

Target matrix

Target	Recommended install
Claude app, Claude Desktop, Cowork	Add marketplace from repository Sendmux/skills, then install Sendmux.
Claude Code	/plugin marketplace add Sendmux/skills, then /plugin install sendmux@sendmux.
Codex app and Codex CLI	codex plugin marketplace add Sendmux/skills, then install Sendmux from Plugins or /plugins.
Agent Skills clients	npx skills add Sendmux/skills.
Single-skill installs	npx skills add Sendmux/skills --skill <skill-name>.

Marketplace plugins and raw Agent Skills only teach workflows. They do not grant Sendmux access. Authorise hosted MCP, create API keys, or use agent access before asking an agent to act on Sendmux data.

Development

This repo uses the Agent Skills format:

skills/
  <skill-name>/
    SKILL.md
    references/
    scripts/
    assets/

Each skill must be validated, benchmarked against a baseline, and packaged before it is marked complete.

Generate Claude and Codex marketplace bundles:

node scripts/build-plugin-bundles.mjs
node scripts/check-plugin-bundles.mjs

The canonical skill source stays in skills/. The generated marketplace plugin lives in plugins/sendmux/ and is checked for drift in CI.

See docs/eval-lint-package-playbook.md for the local eval, lint, package, and install-smoke loop. See docs/regen-update-playbook.md for the source drift check and regeneration procedure.