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Claude Code can connect to hundreds of external tools and data sources through the Model Context Protocol (MCP), an open source standard for AI-tool integrations. MCP servers give Claude Code access to your tools, databases, and APIs. Connect a server when you find yourself copying data into chat from another tool, like an issue tracker or a monitoring dashboard. Once connected, Claude can read and act on that system directly instead of working from what you paste. If you’re connecting your first server, start with the MCP quickstart for a step-by-step walkthrough. This page is the full reference.

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What you can do with MCP

With MCP servers connected, you can ask Claude Code to:
  • Implement features from issue trackers: “Add the feature described in JIRA issue ENG-4521 and create a PR on GitHub.”
  • Analyze monitoring data: “Check Sentry and Statsig to check the usage of the feature described in ENG-4521.”
  • Query databases: “Find emails of 10 random users who used feature ENG-4521, based on our PostgreSQL database.”
  • Integrate designs: “Update our standard email template based on the new Figma designs that were posted in Slack”
  • Automate workflows: “Create Gmail drafts inviting these 10 users to a feedback session about the new feature.”
  • React to external events: an MCP server can also act as a channel that pushes messages into your session, so Claude reacts to Telegram messages, Discord chats, or webhook events while you’re away.

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Find and build MCP servers

Browse reviewed connectors in the Anthropic Directory. Directory connectors use the same MCP infrastructure as Claude Code, so you can add any remote server listed there with claude mcp add.
Verify you trust each server before connecting it. Servers that fetch external content can expose you to prompt injection risk.
To build your own server, see the MCP server guide for protocol fundamentals and the Claude connector building docs for authentication, testing, and Directory submission. You can also have Claude scaffold a server for you with the official mcp-server-dev plugin.
1

Install the plugin

In a Claude Code session, run:
If the install fails, match the message Claude Code reports:
  • Marketplace "claude-plugins-official" not found: add the marketplace with /plugin marketplace add anthropics/claude-plugins-official, then retry the install.
  • The plugin is not found in the marketplace: check the plugin name.
Check the install summary: if it reports Run /reload-plugins to activate., run that command.
2

Run the build skill

Claude asks about your use case and scaffolds a remote HTTP or local stdio server.

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Installing MCP servers

MCP servers can be configured in several ways depending on your needs:

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Option 1: Add a remote HTTP server

HTTP servers are the recommended option for connecting to remote MCP servers. This is the most widely supported transport for cloud-based services.
When configuring MCP servers via JSON in .mcp.json, ~/.claude.json, or claude mcp add-json, the type field accepts streamable-http as an alias for http. The MCP specification uses the name streamable-http for this transport, so configurations copied from server documentation work without modification. A JSON entry that has a url but no type is a configuration error, because Claude Code reads an entry with no type as a stdio server. Claude Code skips that server and reports MCP server "<name>" has a "url" but no "type"; add "type": "http" (or "sse" / "ws") to this entry. Before v2.1.202, Claude Code reported this misconfiguration as command: expected string, received undefined. In --output-format stream-json runs, Claude Code also reports a skipped --mcp-config entry in the system/init event’s mcp_server_errors field, so scripts can detect that the server never loaded. This requires Claude Code v2.1.219 or later.

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Option 2: Add a remote SSE server

The SSE (Server-Sent Events) transport is deprecated. Use HTTP servers instead, where available.
Some services still expose only an SSE endpoint. Use the same command as the HTTP transport, with --transport sse:

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Option 3: Add a local stdio server

Stdio servers run as local processes on your machine. They’re ideal for tools that need direct system access or custom scripts. Claude Code sets CLAUDE_PROJECT_DIR in the spawned server’s environment to the project root, so your server can resolve project-relative paths without depending on the working directory. This is the same directory hooks receive in their CLAUDE_PROJECT_DIR variable. Read it from inside your server process, for example process.env.CLAUDE_PROJECT_DIR in Node or os.environ["CLAUDE_PROJECT_DIR"] in Python. CLAUDE_PROJECT_DIR is the stable project root and doesn’t change when you add or remove working directories mid-session. A server that limits its own filesystem access to a set of allowed directories should implement the MCP roots/list request instead. Claude Code answers roots/list with the session’s launch directory plus every additional working directory you’ve granted with --add-dir, /add-dir, or the additionalDirectories setting. Claude Code sends notifications/roots/list_changed when that set changes. Before v2.1.203, roots/list returned only the launch directory and Claude Code didn’t send notifications/roots/list_changed. This variable is set in the server’s environment, not in Claude Code’s own environment, so referencing it via ${VAR} expansion in the command or args of a project-scoped .mcp.json entry or a local- or user-scoped server entry in ~/.claude.json requires a default such as ${CLAUDE_PROJECT_DIR:-.}. Plugin-provided MCP configurations substitute ${CLAUDE_PROJECT_DIR} directly and don’t need the default.
Important: Separate server arguments with --For stdio servers, the -- (double dash) separates Claude’s own options, such as --transport, --env, and --scope, from the command and arguments that run the server. Everything after -- is passed to the server untouched.For example:
  • claude mcp add --transport stdio myserver -- npx server → runs npx server
  • claude mcp add --env KEY=value --transport stdio myserver -- python server.py --port 8080 → runs python server.py --port 8080 with KEY=value in environment
Without --, Claude Code would try to parse the server’s flags, like --port above, as its own options.--env accepts multiple KEY=value pairs. If the server name comes directly after --env, the CLI reads the name as another pair and rejects it, so place at least one other option between --env and the server name, as in the examples above.

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Option 4: Add a remote WebSocket server

WebSocket servers hold a persistent bidirectional connection, which suits remote MCP servers that push events to Claude unprompted. Use HTTP instead when your server only responds to requests, since HTTP supports OAuth and the claude mcp add --transport flag, while WebSocket supports neither. Configure WebSocket servers in .mcp.json or with claude mcp add-json: