Connect Claude Code to tools via MCP changedmcp

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# Connect Claude Code to tools via MCP

> Learn how to connect Claude Code to your tools with the Model Context Protocol.

Claude Code can connect to hundreds of external tools and data sources through the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/introduction), 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](/docs/en/mcp-quickstart) for a step-by-step walkthrough. This page is the full reference.

## 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](/docs/en/channels) that pushes messages into your session, so Claude reacts to Telegram messages, Discord chats, or webhook events while you're away.

## Find and build MCP servers

Browse reviewed connectors in the [Anthropic Directory](https://claude.ai/directory). Directory connectors use the same MCP infrastructure as Claude Code, so you can add any remote server listed there with `claude mcp add`.

<Warning>
  Verify you trust each server before connecting it. Servers that fetch external content can expose you to [prompt injection risk](/docs/en/security#protect-against-prompt-injection).
</Warning>

To build your own server, see the [MCP server guide](https://modelcontextprotocol.io/docs/develop/build-server) for protocol fundamentals and the [Claude connector building docs](https://claude.com/docs/connectors/building) for authentication, testing, and Directory submission.

You can also have Claude scaffold a server for you with the official [`mcp-server-dev` plugin](https://github.com/anthropics/claude-plugins-official/tree/main/plugins/mcp-server-dev).

<Steps>
  <Step title="Install the plugin">
    In a Claude Code session, run:

    ```
    /plugin install mcp-server-dev@claude-plugins-official
    ```

    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](/docs/en/discover-plugins#install-plugins): check the plugin name.

    Check the install summary: if it reports `Run /reload-plugins to activate.`, run that command.
  </Step>

  <Step title="Run the build skill">
    ```
    /mcp-server-dev:build-mcp-server
    ```

    Claude asks about your use case and scaffolds a remote HTTP or local stdio server.
  </Step>
</Steps>

## Installing MCP servers

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

### 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.

```bash theme={null}
# Basic syntax
claude mcp add --transport http <name> <url>

# Real example: Connect to Notion
claude mcp add --transport http notion https://mcp.notion.com/mcp

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

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](/docs/en/headless#stream-responses), so scripts can detect that the server never loaded. This requires Claude Code v2.1.219 or later.

### Option 2: Add a remote SSE server

<Warning>
  The SSE (Server-Sent Events) transport is deprecated. Use HTTP servers instead, where available.
</Warning>

Some services still expose only an SSE endpoint. Use the same command as the HTTP transport, with `--transport sse`:

```bash theme={null}
# Basic syntax
claude mcp add --transport sse <name> <url>

# Real example: Connect to Asana
claude mcp add --transport sse asana https://mcp.asana.com/sse

# Example with authentication header
claude mcp add --transport sse private-api https://api.company.com/sse \
  --header "X-API-Key: your-key-here"
```

### 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](/docs/en/permissions#working-directories) 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.

```bash theme={null}
# Basic syntax
claude mcp add [options] <name> -- <command> [args...]

# Real example: Add Airtable server
claude mcp add --env AIRTABLE_API_KEY=YOUR_KEY --transport stdio airtable \
  -- npx -y airtable-mcp-server
```

<Note>
  **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.
</Note>

### 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`:

```bash theme={null}
claude mcp add-json events-server \
  '{"type":"ws","url":"wss://mcp.example.com/socket","headers":{"Authorization":"Bearer YOUR_TOKEN"}}'
```

The `type: "ws"` entry accepts the same `url`, `headers`, `headersHelper`, `timeout`, and `alwaysLoad` fields as `http`. Authentication is header-only, so pass a static token in `headers` or generate one at connect time with [`headersHelper`](#use-dynamic-headers-for-custom-authentication). The `claude mcp add --transport` flag doesn't accept `ws`.

### Managing your servers

Once configured, you can manage your MCP servers with these commands:

```bash theme={null}
# List all configured servers
claude mcp list

# Get details for a specific server
claude mcp get notion

# Remove a server
claude mcp remove notion

# (within Claude Code) Check server status
/mcp
```

#### Server status

`claude mcp add` confirms a successful add by printing an `Added ...` line, which means the configuration was written. `claude mcp list` then shows a health status next to each server it lists, such as `✔ Connected`, `! Needs authentication`, or `✘ Failed to connect`. A failure status means Claude Code couldn't connect to that server, not that the list command failed.

Project-scoped servers from `.mcp.json` that are awaiting your approval appear in `claude mcp list` and `claude mcp get <name>` as ``⏸ Pending approval (run `claude` to approve)``. Run `claude` interactively to review and approve them. `claude mcp get <name>` shows rejected servers as `✘ Rejected (see disabledMcpjsonServers in settings)`.

WebSocket servers don't appear in `claude mcp list` output. Use `claude mcp get <name>` or the `/mcp` panel to check them.

#### Project server approvals and workspace trust

As of v2.1.196, `claude mcp list` and `claude mcp get` read `.mcp.json` approvals only from settings files that aren't checked into the repository until you trust the workspace by running `claude` in it and accepting the workspace trust dialog. A cloned repository can't approve its own servers: [`enableAllProjectMcpServers` or `enabledMcpjsonServers`](/docs/en/settings#available-settings) committed to the project's `.claude/settings.json` is ignored in an untrusted folder, and the server stays at `⏸ Pending approval` instead of being connected and health-checked.

Approvals from these sources still apply in an untrusted folder:

* your user `~/.claude/settings.json`
* managed settings
* settings passed with `--settings`

Approvals in an untracked `.claude/settings.local.json` also apply, but only after you accept a trust dialog for that folder or one of its parent directories: Claude Code runs git to check whether the file is tracked, and it runs that check only in a trusted folder. In a folder you've never trusted, the file's approvals wait for the trust dialog unless the folder is your own configuration home: your home directory, or a directory whose `.claude` you've set as [`CLAUDE_CONFIG_DIR`](/docs/en/env-vars). Before v2.1.207, an untracked `.claude/settings.local.json` approved servers in a folder you'd never trusted.

A `disabledMcpjsonServers` entry in any settings file still rejects the server.

#### Server status detail

In `/mcp`, a server's menu, and the [`/plugin`](/docs/en/plugins) manager, a remote (HTTP or SSE) server you've used before can show a `cached` status such as `cached 2h ago · connects on first use · 5 tools`. Claude Code loaded the server's tool list from a previous session instead of connecting at startup, and it connects the server the first time Claude calls one of its tools. The tools are available from your first message, so you don't need to do anything. To make every server connect at startup instead, set [`MCP_DISCOVERY_CACHE=0`](/docs/en/env-vars). The discovery cache and its `cached` status require Claude Code v2.1.221 or later.

When a server's status is `✘ Failed to connect`, `claude mcp list` appends the failure detail to that status line, and `claude mcp get <name>` shows it on an `Issue:` line: the HTTP status or error code, plus any error text the server returned. The server's detail view in `/mcp` includes the same server-reported text in its `Issue:` row. Claude Code redacts credential-like text from this detail and never includes the expanded server URL, which can carry secrets. Claude Code appends no detail to a `✘ Connection error` status, because the exception text it would print there can embed that URL. Before v2.1.219, both commands showed only the bare failure status, without the status code or the server's error text.

A remote server whose configuration has an empty `url` shows as `not configured` in `/mcp`, in `claude mcp list`, and in the [`/plugin`](/docs/en/plugins) manager, and Claude Code doesn't attempt to connect to it. A plugin can include a placeholder entry like this for a connector you configure later, so Claude Code doesn't report it as an error or a setup issue. The server's detail view in `/mcp` reads `No URL configured for this server`; set the entry's `url` to connect it. Before v2.1.208, Claude Code reported an empty `url` as a configuration issue with a prompt to reconnect.

#### Configuration warnings

Claude Code also warns when an MCP config value carries hidden leading or trailing whitespace, which often comes from pasting a token with a trailing newline. Claude Code checks `command`, `url`, each `args` entry, and the values and key names under `env` and `headers`. Claude Code shows the warning in `claude mcp list` output and in `/mcp`, naming the affected fields without echoing their values, for example `Leading or trailing whitespace in: headers.Authorization`. Claude Code doesn't trim the whitespace and uses the values exactly as written, so edit the configuration to remove it.

Some server names are reserved for Claude Code's built-in servers: `workspace`, `claude-in-chrome`, `computer-use`, `Claude Preview`, and `Claude Browser`. If your configuration defines a server with a reserved name, Claude Code skips it at load time and shows a warning asking you to rename it. `claude mcp add` rejects a reserved name with an error.

`Claude Preview` and `Claude Browser` both name the built-in server that the [Claude Code desktop app's preview pane](/docs/en/desktop#preview-your-app) uses. Before v2.1.205, `Claude Browser` wasn't reserved, so a user-configured server could register under that name.

#### Tool availability

The `/mcp` panel shows the tool count next to each connected server and flags servers that advertise the tools capability but expose no tools.

If your request needs tools from a server that is still connecting in the background, Claude waits for that server before continuing. How the wait happens depends on your configuration:

* **With [tool search](#scale-with-mcp-tool-search), the default**: the wait happens inside the `ToolSearch` call.
* **Without tool search**: Claude uses the `WaitForMcpServers` tool instead. Configurations without tool search include a custom `ANTHROPIC_BASE_URL`, `ENABLE_TOOL_SEARCH=false`, and a model earlier than the Claude 4.5 generation on Google Cloud's Agent Platform.
* **On a Microsoft Foundry [deployment hosted on Azure](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry#hosting-options)**: Claude starts on the tool-search path rather than with `WaitForMcpServers`, since Claude Code discovers the deployment's server-side rejection only from the API. After Claude Code switches that deployment to [upfront loading](#scale-with-mcp-tool-search), tools from a server that finishes connecting become available on Claude's next request.

With tool search enabled, when a server finishes connecting while Claude is working, Claude Code lists the server's tool names to Claude on its next request in the same turn. Claude can then search for and call those tools without waiting for your next message.

### Disable a server without removing it

Toggle a server off in the `/mcp` panel to stop Claude Code from connecting to it without losing its configuration. Claude Code still lists the server in `/mcp`, marked as disabled.

When you toggle a server, Claude Code records your choice per project in `~/.claude.json`, in one of two lists that cover disjoint sets of servers:

* `disabledMcpServers`: an opt-out list for user-configured servers, plugin servers, claude.ai connectors, and built-in servers that default to on. Claude Code doesn't connect to a server you list here. When you disable a claude.ai connector with the per-project `/mcp` toggle described in [Disable claude.ai connectors](#disable-claude-ai-connectors), Claude Code writes it to this list under its display name, for example `claude.ai Slack`.
* `enabledMcpServers`: an opt-in list for built-in servers that default to off, such as `computer-use`. Claude Code connects to a default-off server only when you list it here.

Claude Code consults exactly one of the two lists for each server, so neither list overrides the other. If you add a regular server to `enabledMcpServers`, or a default-off built-in server to `disabledMcpServers`, Claude Code ignores the entry.

`disabledMcpServers` and `enabledMcpServers` are unrelated to [`enabledMcpjsonServers` and `disabledMcpjsonServers`](/docs/en/settings#available-settings), which control approval of servers defined in a project's `.mcp.json` file.

### Dynamic tool updates

Claude Code supports MCP `list_changed` notifications, allowing MCP servers to dynamically update their available tools, prompts, and resources without requiring you to disconnect and reconnect. When an MCP server sends a `list_changed` notification, Claude Code automatically refreshes the available capabilities from that server.

If a refresh request fails, Claude Code keeps the server's previously discovered tools, prompts, and resources until a later refresh succeeds. Before v2.1.214, a transient error during the refresh replaced the server's tools, prompts, and resources with an empty list.

### Automatic reconnection

If an HTTP or SSE server disconnects mid-session, Claude Code automatically reconnects with exponential backoff: up to five attempts, starting at a one-second delay and doubling each time. The server appears as pending in `/mcp` while reconnection is in progress. After five failed attempts the server is marked as failed and you can retry manually from `/mcp`. Stdio servers are local processes and are not reconnected automatically.

The same backoff applies when an HTTP or SSE server fails its initial connection at startup. Claude Code retries the initial connection up to three times on transient errors such as a 5xx response, a connection refused, or a timeout, then marks the server as failed if it still can't connect. Authentication and not-found errors are not retried because they require a configuration change to resolve.

When a configured server fails to connect, Claude Code tells Claude which server failed and its connection error, including in `ToolSearch` results that find no matching tool, so Claude reports the connection failure in its response. Requires [tool search](#scale-with-mcp-tool-search), which is enabled by default. In configurations without tool search, such as a custom `ANTHROPIC_BASE_URL`, `ENABLE_TOOL_SEARCH=false`, or a model that doesn't support tool search, and on Amazon Bedrock, Google Cloud's Agent Platform, and Microsoft Foundry, Claude Code doesn't report failed server connections to Claude.

The capability discovery requests that run after a successful connection, such as `tools/list`, `prompts/list`, and `resources/list`, also retry transient network and server errors up to three times with short backoff. Authentication errors, 4xx responses, and request timeouts are not retried.

### Push messages with channels

An MCP server can also push messages directly into your session so Claude can react to external events like CI results, monitoring alerts, or chat messages. To enable this, your server declares the `claude/channel` capability and you opt it in with the `--channels` flag at startup. See [Channels](/docs/en/channels) to use an officially supported channel, or [Channels reference](/docs/en/channels-reference) to build your own.

<Tip>
  Tips:

  * Use the `-s` or `--scope` flag to specify where the configuration is stored:
    * `local` (default): available only to you in the current project
    * `project`: shared with everyone in the project via the `.mcp.json` file
    * `user`: available to you across all projects
  * Set environment variables with `-e` or `--env` flags (for example, `-e KEY=value`)
  * The `--transport` and `--header` flags also accept `-t` and `-H` short forms
  * Configure MCP server startup timeout using the `MCP_TIMEOUT` environment variable (for example, `MCP_TIMEOUT=10000 claude` sets a 10-second timeout)
  * Set a per-server tool execution timeout by adding a `timeout` field in milliseconds to that server's `.mcp.json` entry, for example `"timeout": 600000` for ten minutes. This overrides the `MCP_TOOL_TIMEOUT` environment variable for that server only
  * Claude Code displays a warning when MCP tool output exceeds 10,000 tokens and limits output to 25,000 tokens by default. To raise the limit, set the `MAX_MCP_OUTPUT_TOKENS` environment variable (for example, `MAX_MCP_OUTPUT_TOKENS=50000`); the warning threshold is fixed. See [MCP output limits and warnings](#mcp-output-limits-and-warnings)
  * Use `/mcp` to authenticate with remote servers that require OAuth 2.0 authentication
</Tip>

The per-server `timeout` is a hard wall-clock limit per tool call, and progress notifications from the server don't extend it. Values below 1000 are ignored and fall through to `MCP_TOOL_TIMEOUT`, or to its default of about 28 hours when that variable is unset. For an HTTP, SSE, or [claude.ai connector](/docs/en/mcp#use-mcp-servers-from-claude-ai) server there is also a second, per-request timer that covers each request through to the server's first response byte. That timer is 60 seconds unless you set the per-server `timeout` or `MCP_TOOL_TIMEOUT`; setting either to 60 seconds or higher raises the per-request timer to that value, a lower value doesn't shorten it, and the 28-hour default of an unset `MCP_TOOL_TIMEOUT` never feeds it. Stdio and WebSocket servers have no per-request timer. Before v2.1.162, values below 1000 were floored to one second instead.

A per-server `timeout` of at least 1000 also acts as a floor on the idle timeout described below: Claude Code never aborts that server's tool calls for idleness sooner than the per-server `timeout`. Requires Claude Code v2.1.203 or later.

A tool call to an MCP server that sends no response and no progress notification for the idle window aborts with an error instead of waiting for the wall-clock limit. The idle timeout requires Claude Code v2.1.187 or later. It applies to every server type except IDE servers and SDK in-process servers. The idle window defaults to five minutes for HTTP, SSE, WebSocket, and [claude.ai connector](#use-mcp-servers-from-claude-ai) servers, and to 30 minutes for stdio servers. Before v2.1.203, stdio servers were exempt from the idle timeout.

Set the [`CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT`](/docs/en/env-vars) environment variable in milliseconds to change the idle window, or set it to `0` to disable the check.

These timeouts bound how long a call can run, not always how long it blocks the session: a main-conversation call that runs past two minutes moves to a background task first. See [Automatic backgrounding of long tool calls](#automatic-backgrounding-of-long-tool-calls).

### Automatic backgrounding of long tool calls

An MCP tool call in the main conversation that is still running after two minutes moves to a background task instead of blocking the session. Claude receives the task ID immediately and keeps working, and the result arrives as a task notification when the call settles. Automatic backgrounding requires Claude Code v2.1.212 or later.

The task appears in [`/tasks`](/docs/en/commands#all-commands), where you can also stop it, and it doesn't survive exiting the session. The per-call limits still apply while the call runs in the background: the wall-clock limit set by the per-server `timeout` or [`MCP_TOOL_TIMEOUT`](/docs/en/env-vars), and the idle timeout set by [`CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT`](/docs/en/env-vars).

Set the [`CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS`](/docs/en/env-vars) environment variable in milliseconds to change the threshold, or set it to `0` to turn automatic backgrounding off. Setting `CLAUDE_CODE_DISABLE_BACKGROUND_TASKS` to `1` also turns it off, along with all other background task features.

Some calls never move to the background:

* Calls from [subagents](/docs/en/sub-agents); Claude Code backgrounds only main-conversation calls
* Calls to IDE servers
* Calls in [non-interactive mode](/docs/en/headless), unless `CLAUDE_AUTO_BACKGROUND_TASKS` is set to `1`, since a one-shot run can end before the result arrives

A call waiting on an open [elicitation dialog](#respond-to-mcp-elicitation-requests) isn't backgrounded while the dialog is open; the server is blocked on your input, not slow, so Claude Code defers the move until the dialog closes.

### Plugin-provided MCP servers

[Plugins](/docs/en/plugins) can bundle MCP servers that provide tools and integrations when you enable the plugin. Plugin MCP servers work identically to user-configured servers.

**How plugin MCP servers work**:

* Plugins define MCP servers in `.mcp.json` at the plugin root or inline in `plugin.json`

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