Using Corsair

Tools for agents

Agent email is plain HTTP, so any agent can use it. These make it one step: a skill that teaches the agent the signup flow and its cautions, and an MCP server that gives it tools instead of curl commands. Both ship in one Claude Code plugin, and each also works on its own in any harness.

Everything here needs two values from the control panel's Agent email page:

Variable	Value
`CORSAIR_URL`	Your server, e.g. `https://mail.example.com`
`CORSAIR_AGENT_TOKEN`	The agent's API key, starting `ca_` (shown once). Also its password for IMAP, POP3, SMTP and HTTP Basic auth

Claude Code: the plugin#

Adds the skill and the MCP server together.

export CORSAIR_URL=https://mail.example.com
export CORSAIR_AGENT_TOKEN=ca_...

claude plugin marketplace add wess/corsair
claude plugin install corsair-agent-email@corsair

Or, inside a session: /plugin marketplace add wess/corsair, then /plugin install corsair-agent-email@corsair. Start a new session afterwards. The MCP server reads the two variables from the environment claude was started in.

Any harness: the skill#

A skill is one SKILL.md file. Put it where your harness looks for skills — ~/.claude/skills/ for Claude Code, .agents/skills/ or the equivalent for others — in a folder named agent-email:

mkdir -p ~/.claude/skills/agent-email
curl -fsSL -o ~/.claude/skills/agent-email/SKILL.md \
  https://raw.githubusercontent.com/wess/corsair/main/plugin/skills/agent-email/SKILL.md

It works without the MCP server: it tells the agent the same operations as curl calls against CORSAIR_URL.

Any harness: the MCP server#

A single file with no dependencies, run by Node 18 or newer, or Bun.

mkdir -p ~/.corsair
curl -fsSL -o ~/.corsair/agent-email-mcp.mjs \
  https://raw.githubusercontent.com/wess/corsair/main/plugin/mcp/server.mjs

Then register it with your harness. Most take the same JSON:

json

{
  "mcpServers": {
    "corsair-agent-email": {
      "command": "node",
      "args": ["/home/you/.corsair/agent-email-mcp.mjs"],
      "env": {
        "CORSAIR_URL": "https://mail.example.com",
        "CORSAIR_AGENT_TOKEN": "ca_..."
      }
    }
  }
}

Claude Code can do it in one command:

claude mcp add corsair-agent-email \
  -e CORSAIR_URL=https://mail.example.com \
  -e CORSAIR_AGENT_TOKEN=ca_... \
  -- node ~/.corsair/agent-email-mcp.mjs

Read the file before you run it; it is about two hundred lines and talks only to your own server.

The tools#

Tool	Does
`agent_email_address`	The address to sign up with.
`wait_for_email`	Waits for a new message, returns it with `links` and `codes`.
`list_emails`	Recent mail, newest first.
`read_email`	One message in full.
`download_attachment`	An attachment, as base64, up to 1 MB.
`send_email`	Send or reply, if sending is on for this agent.

For models: `llms.txt`#

The site publishes /llms.txt, an index of these docs for a model, and /llms-full.txt, every page in one file.

Check it works#

Ask the agent for its address, send mail to it from anywhere, then ask it to wait for the message. If the tools error with "Set CORSAIR_URL and CORSAIR_AGENT_TOKEN", the harness did not pass the environment through — put the values in the server's env block instead of relying on your shell.