Agent Skills

The SendAPI Agent Skill for Claude teaches it how to send well — choosing the right channel, running the OTP verify flow, applying bulk‑send guardrails, and acting on error codes instead of blindly retrying.

The Skill is the know‑how; the MCP server is the tools. Paired, they are strongest. The Skill also works on its own through the REST API.

What the Skill includes

• Channel selection — when to use SMS vs WhatsApp vs email vs the OTP flow, and to ask rather than guess.
• Sending contracts — the required fields for each channel (to in E.164, session_id for WhatsApp, subject + html/text for email, and so on).
• OTP / 2FA flow — send_otp then check_otp, with the rule to never invent or echo a code.
• Bulk‑send guardrails — always show the recipient count and message and get explicit confirmation before a bulk send.
• Error handling — act on error.code (sending_limited, content_blocked, invalid_from_domain, validation errors) instead of hammering retries.

Install

Claude Code (plugin)

Install the Skill and the MCP server together in one step from the SendAPI-co/sendapi-skills marketplace:

/plugin marketplace add SendAPI-co/sendapi-skills
/plugin install sendapi

Then set your key so the bundled MCP server can authenticate:

export SENDAPI_API_KEY=sk_live_xxxx   # from your dashboard

Manual install

Prefer to copy the files yourself? Grab them from the repo and drop the skill into your skills directory, then restart Claude Code (or run /skills):

mkdir -p ~/.claude/skills/sendapi
cp -r skills/sendapi/SKILL.md skills/sendapi/references ~/.claude/skills/sendapi/

For a single project, place it at .claude/skills/sendapi/ instead. On Claude Desktop, add the folder under your skills directory and enable it in Settings.

Use it with the MCP server

For the best experience, also connect the MCP server so Claude has real tools to call:

claude mcp add --transport http sendapi https://sendapi.co/mcp \
  --header "Authorization: Bearer sk_live_xxxx"

Then just ask:

"Send an SMS to +1 555 000 0000 letting them know their order shipped."

The Skill guides Claude to confirm the recipient and content, pick the channel, and call the right tool.

Requirements

• Claude Code or Claude Desktop, with the skills directory enabled.
• Recommended: the SendAPI MCP server connected, so Claude has tools to call.
• Standalone (no MCP): a SendAPI API key in the environment as SENDAPI_API_KEY for the REST fallback. The Skill reads it from the environment and never hardcodes or prints it.

Related

• MCP Server — the tools the Skill drives.
• AI Agents & Automations — other ways to let agents and automations send.