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Connect Claude Code to Tools via MCP

Official guide for connecting Claude Code to external tools and data sources through the Model Context Protocol. Source: https://code.claude.com/docs/en/mcp.md Added: 2026-01-29

Overview​

MCP (Model Context Protocol) is an open source standard for AI-tool integrations. MCP servers give Claude Code access to tools, databases, and APIs.

What You Can Do​

  • Implement features from issue trackers (JIRA, GitHub)
  • Analyze monitoring data (Sentry, Statsig)
  • Query databases (PostgreSQL, etc.)
  • Integrate designs (Figma)
  • Automate workflows (Gmail, Slack)

Installing MCP Servers​

claude mcp add --transport http notion https://mcp.notion.com/mcp
claude mcp add --transport http secure-api https://api.example.com/mcp \
  --header "Authorization: Bearer your-token"

Option 2: SSE (Deprecated)​

claude mcp add --transport sse asana https://mcp.asana.com/sse

Option 3: Stdio (Local)​

claude mcp add --transport stdio --env AIRTABLE_API_KEY=YOUR_KEY airtable \
  -- npx -y airtable-mcp-server

All options (--transport, --env, --scope, --header) must come before the server name. -- separates the name from the command.

Managing Servers​

claude mcp list          # List all
claude mcp get github    # Details
claude mcp remove github # Remove
/mcp                     # Status (within Claude Code)

Installation Scopes​

ScopeStorageWho Sees ItUse Case
Local (default)~/.claude.jsonYou, this projectPersonal dev servers, sensitive credentials
Project.mcp.json in repo rootAll collaboratorsTeam-shared tools (check into VCS)
User~/.claude.jsonYou, all projectsPersonal utilities across projects
claude mcp add --transport http stripe --scope local https://mcp.stripe.com
claude mcp add --transport http paypal --scope project https://mcp.paypal.com/mcp
claude mcp add --transport http hubspot --scope user https://mcp.hubspot.com/anthropic

Precedence: local > project > user.

Authentication​

OAuth 2.0 supported for remote servers:

  1. Add the server
  2. Run /mcp within Claude Code
  3. Follow browser login steps

Environment Variable Expansion in .mcp.json​

{
  "mcpServers": {
    "api-server": {
      "type": "http",
      "url": "${API_BASE_URL:-https://api.example.com}/mcp",
      "headers": {
        "Authorization": "Bearer ${API_KEY}"
      }
    }
  }
}

Supported: ${VAR} and ${VAR:-default} in command, args, env, url, headers.

MCP Resources​

Reference resources with @ mentions:

> Can you analyze @github:issue://123 and suggest a fix?
> Compare @postgres:schema://users with @docs:file://database/user-model

Automatically enabled when MCP tool descriptions exceed 10% of context window. Tools load on-demand instead of all upfront.

ENABLE_TOOL_SEARCH=auto:5 claude   # Custom 5% threshold
ENABLE_TOOL_SEARCH=false claude    # Disable

Requires Sonnet 4+ or Opus 4+.

Plugin MCP Servers​

Plugins can bundle MCP servers in .mcp.json at plugin root or inline in plugin.json. Start automatically when plugin enabled.

Managed MCP Configuration​

Option 1: Exclusive Control (managed-mcp.json)​

System-wide file that takes exclusive control:

  • macOS: /Library/Application Support/ClaudeCode/managed-mcp.json
  • Linux: /etc/claude-code/managed-mcp.json

Option 2: Policy-Based (allowedMcpServers / deniedMcpServers)​

Allow users to add servers within policy constraints. Restrict by:

  • Server name: { "serverName": "github" }
  • Command: { "serverCommand": ["npx", "-y", "approved-package"] }
  • URL pattern: { "serverUrl": "https://mcp.company.com/*" }

Denylist always takes absolute precedence.

Claude Code as MCP Server​

claude mcp serve

Use in Claude Desktop config:

{
  "mcpServers": {
    "claude-code": {
      "type": "stdio",
      "command": "claude",
      "args": ["mcp", "serve"]
    }
  }
}

Output Limits​

  • Warning threshold: 10,000 tokens
  • Default max: 25,000 tokens
  • Override: MAX_MCP_OUTPUT_TOKENS=50000