skill CX Codex

agentmail-mcp — Claude Code skill: what it does, how to install

Q: How to install agentmail-mcp in Claude Code?

Run `npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a claude-code`. The skill file will be placed in `~/.claude/skills/agentmail-mcp/SKILL.md`.

Configures and debugs the hosted AgentMail MCP endpoint for Claude Code, Cursor, and Codex. It helps with OAuth, API key headers, and handshake failures.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a claude-code

Open on GitHub

What agentmail-mcp does

This skill guides the setup of the remote AgentMail service at https://mcp.agentmail.to/mcp. Using the hosted HTTP endpoint bypasses running a local Node.js worker and keeps tool schemas current without package updates.

Integration relies on adding the HTTP endpoint into your editor configuration or running claude mcp add. Authentication supports browser OAuth or the x-api-key header linked to the AGENTMAIL_API_KEY environment variable. A 404 status typically indicates a missing /mcp suffix in the URL.

Use this guide strictly for setup and diagnostics. Routine tasks like sending messages or inspecting mailboxes belong to sibling action skills.

What it helps with

connect the hosted AgentMail server via streamable HTTP
configure browser OAuth or header-based API key authentication
resolve 401 unauthorized and 404 missing endpoint errors
verify available tool schemas with a read-only smoke check

Example prompts for the agent

Configure the AgentMail MCP connection in Claude Code using OAuth.
Troubleshoot a 401 unauthorized error when connecting to AgentMail.
Set up the x-api-key header with AGENTMAIL_API_KEY in my MCP config.

How to install agentmail-mcp

1Skills CLI (Vercel)

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a claude-code

2Manually: put the files in place

~/.claude/skills/agentmail-mcp/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/agentmail-mcp/

1Skills CLI (Vercel)

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a codex

2Manually: put the files in place

.agents/skills/agentmail-mcp/SKILL.md

For all projects use ~/.agents/skills/

1Skills CLI (Vercel)

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a cursor

2Manually: put the files in place

.cursor/skills/agentmail-mcp/SKILL.md

Cursor also reads .agents/skills/ and .claude/skills/

1GitHub CLI

gh skill install agentmail-to/agentmail-skills agentmail-mcp

2Manually: put the files in place

.github/skills/agentmail-mcp/SKILL.md

1Skills CLI (Vercel)

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a gemini-cli

2Platform CLI

gemini skills install https://github.com/agentmail-to/agentmail-skills --path agentmail-mcp

Manually: put the files in place

.devin/skills/agentmail-mcp/SKILL.md

The legacy .windsurf/skills/ path still works

Skills CLI (Vercel)

npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a opencode

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about agentmail-mcp

How to install agentmail-mcp in Claude Code?

Run npx skills add agentmail-to/agentmail-skills --skill agentmail-mcp -a claude-code. The skill file will be placed in ~/.claude/skills/agentmail-mcp/SKILL.md.

What does the agentmail-mcp skill do?

It provides setup instructions and diagnostic steps for connecting editors to the hosted AgentMail MCP server. It is not designed for routine email composition or inbox reading.

What causes a 404 status during server connection?

A 404 response usually points to an incomplete URL path. Ensure the configuration includes the /mcp path, matching https://mcp.agentmail.to/mcp.

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