Kernel MCP Server

Kernel MCP Server

A Model Context Protocol (MCP) server that provides AI assistants with secure access to Kernel platform tools and browser automation capabilities.

🌐 Use instantly at https://mcp.onkernel.com/mcp — no installation required!

What is this?

The Kernel MCP Server bridges AI assistants (like Claude, Cursor, fx, or other MCP-compatible tools) with the Kernel platform, enabling them to:

• 🚀 Deploy and manage Kernel apps in the cloud
• 🌐 Launch and control headless Chromium sessions for web automation
• 📊 Monitor deployments and track invocations
• 🔍 Search Kernel documentation and inject context
• 💻 Execute arbitrary Playwright code against live browsers
• 🧠 Run persistent JavaScript Browser REPL cells with native helpers, Patchright, Playwright, and raw CDP
• 🎥 Record MP4 video replays of browser automation

Open-source & fully-managed — the complete codebase is available here, and we run the production instance so you don't need to deploy anything.

The server uses OAuth 2.0 authentication via Clerk to ensure secure access to your Kernel resources. During authorization, users can grant organization-wide access or restrict the resulting access and refresh tokens to one Kernel project. Project-scoped tokens cannot switch projects; organization-wide authorization remains available for existing workflows.

For a deeper dive into why and how we built this server, see our blog post: Introducing Kernel MCP Server.

Setup Instructions

General (Transports)

• Streamable HTTP (recommended): https://mcp.onkernel.com/mcp
• stdio via mcp-remote (for clients without remote MCP support): npx -y mcp-remote https://mcp.onkernel.com/mcp

Use the streamable HTTP endpoint where supported for increased reliability. If your client does not support remote MCP, use mcp-remote over stdio.

Kernel's server is a centrally hosted, authenticated remote MCP using OAuth 2.1 with dynamic client registration.

Protocol compatibility

The same /mcp endpoint serves SDK v1 / 2025-era Streamable HTTP clients and protocol revision 2026-07-28 clients through the SDK v2 stateless handler. Legacy clients still initialize normally. Modern clients use per-request metadata and do not initialize or receive an MCP session ID. Both use the same tools and authentication checks; MCP Apps capabilities are read per request for modern clients.

Legacy clients should handle both JSON-RPC errors and isError tool results. Unknown tools now produce JSON-RPC error -32602; ordinary tool failures still return isError. Validation-error text and generated tool schemas can differ from SDK v1. No byte-preserving compatibility layer or Tasks extension is installed.

Run bun test 'src/app/[transport]/dual-era.test.ts' to exercise both SDK client generations over HTTP, including OAuth authorization and refresh with local upstream service fixtures. The v1 SDK is retained only as a test dependency.

Quick Setup with Kernel CLI

The fastest way to configure the MCP server is using the Kernel CLI:

# Install the CLI

brew install onkernel/tap/kernel

or: npm install -g @onkernel/cli

Install MCP for your tool

kernel mcp install --target

Supported Targets

The CLI automatically locates your tool's config file and adds the Kernel MCP server configuration.

Connect in your client

Claude

Our remote MCP server is not compatible with the method Free users of Claude use to add MCP servers.

Pro, Max, Team & Enterprise (Claude.ai and Claude Desktop)

1. Go to Settings → Connectors → Add custom connector.
2. Enter: Integration name: Kernel, Integration URL: https://mcp.onkernel.com/mcp, then click Add.
3. In Settings → Connectors, click Connect next to Kernel to launch OAuth and approve.
4. In chat, click Search and tools and enable the Kernel tools if needed.

On Claude for Work (Team/Enterprise), only Primary Owners or Owners can enable custom connectors for the org. After it's configured, each user still needs to go to Settings → Connectors and click Connect to authorize it for their account.

Claude Code CLI

claude mcp add --transport http kernel https://mcp.onkernel.com/mcp

Then in the REPL run once to authenticate:

/mcp

Cursor

Automatic setup

Manual setup

1. Press ⌘/Ctrl Shift J.
2. Go to MCP & Integrations → New MCP server.
3. Add this configuration:

{

"mcpServers": { "kernel": { "url": "https://mcp.onkernel.com/mcp" } } }

1. Save. The server will appear in Tools.

OpenCode

Add the following to your ~/.config/opencode/opencode.jsonc:

{

"mcp": { "kernel": { "type": "remote", "url": "https://mcp.onkernel.com/mcp", }, }, }

Then authenticate using the OpenCode CLI:

# Authenticate with Kernel

opencode mcp auth kernel

If you need to re-authenticate, first logout then auth again

opencode mcp logout kernel opencode mcp auth kernel

fx

Configure Kernel with the Kernel CLI:

kernel mcp install --target fx

Or add Kernel to the mcp map in ~/.fx/mcp.json manually:

{

"mcp": { "kernel": { "type": "http", "url": "https://mcp.onkernel.com/mcp", "oauth": {} } } }

Start fx, or reload the configuration in an existing session:

/mcp reload

Then authenticate with Kernel:

/mcp auth kernel --open

Authorize access in the browser window that opens. Run /mcp list to verify that Kernel is connected.

Goose

Click here to install Kernel on Goose in one click.

Goose Desktop

1. Click Extensions in the sidebar of the Goose Desktop.
2. Click Add custom extension.
3. On the Add custom extension modal, enter:

• Extension Name: Kernel
• Type: STDIO
• Description: Access Kernel's cloud-based browsers via MCP
• Command: npx -y mcp-remote https://mcp.onkernel.com/mcp
• Timeout: 300

1. Click Save Changes button.

Goose CLI

1. Run the following command:

   goose configure

1. Select Add Extension from the menu.
2. Choose Command-line Extension.
3. Follow the prompts:

• Extension name: Kernel
• Command: npx -y mcp-remote https://mcp.onkernel.com/mcp
• Timeout: 300
• Description: Access Kernel's cloud-based browsers via MCP

Visual Studio Code

{

"mcpServers": { "kernel": { "url": "https://mcp.onkernel.com/mcp", "type": "http" } } }

1. Press ⌘/Ctrl P → search MCP: Add Server.
2. Select HTTP (HTTP or Server-Sent Events).
3. Enter: https://mcp.onkernel.com/mcp
4. Name the server Kernel → Enter.

Windsurf

1. Press ⌘/Ctrl , to open settings.
2. Navigate Cascade → MCP servers → View raw config.
3. Paste:

{

"mcpServers": { "kernel": { "command": "npx", "args": ["-y", "mcp-remote", "https://mcp.onkernel.com/mcp"] } } }

1. On Manage MCPs, click Refresh to load Kernel MCP.

Zed

1. Press ⌘/Ctrl , to open settings.
2. Paste:

{

"context_servers": { "kernel": { "source": "custom", "command": "npx", "args": ["-y", "mcp-remote", "https://mcp.onkernel.com/mcp"] } } }

Smithery

You can connect directly to https://mcp.onkernel.com/mcp, or use Smithery as a proxy using its provided URL.

• Use Smithery URL in any MCP client:

1. Open Smithery: Kernel.
2. Copy the URL from "Get connection URL".
3. Paste it into your MCP client's "Add server" flow.

• Use Kernel in Smithery's Playground MCP client:

1. Open Smithery Playground.
2. Click "Add servers", search for "Kernel", and add it.
3. Sign in and authorize Kernel when prompted.

Others

Many other MCP-capable tools accept:

• Command: npx
• Arguments: -y mcp-remote https://mcp.onkernel.com/mcp

{

"kernel": { "command": "npx", "args": ["-y", "mcp-remote", "https://mcp.onkernel.com/mcp"] } }

Configure these values wherever the tool expects MCP server settings.

Tools

Each Kernel feature has a single manage_* tool with an action parameter, keeping the tool set small and consistent. Standalone tools handle high-frequency and interactive workflows.

One additional Managed Auth helper (begin_auth_login) is marked app-only (_meta.ui.visibility: ["app"]); it refuses to execute on hosts that do not declare MCP Apps support. The App forwards the server-issued signed flow checkpoint to the shared manage_auth_connections wait action, so flow identity and terminal-state decisions stay on the server.

Self-hosted deployments can select tool families with KERNEL_MCP_ENABLED_TOOLSETS or hide them with KERNEL_MCP_DISABLED_TOOLSETS. Both accept comma- or space-separated toolset names and standalone aliases. For example, KERNEL_MCP_ENABLED_TOOLSETS="playwright repl computer" exposes browser-control tools without browser lifecycle or managed-auth tools, while KERNEL_MCP_DISABLED_TOOLSETS=api_keys only removes manage_api_keys. get_connection_context remains available in either mode.

Call get_connection_context before deciding whether to create or select a project. Its canonical connection_scope reports whether the connection is organization-wide or fixed to a project. Project-scoped tools advertise an optional project (name or ID) and a deprecated project_id: organization-wide connections may omit them to preserve organization-wide reads and API default-project behavior, while fixed-project connections may omit them or pass the matching project. Project resources use project-qualified kernel://orgs/{organizationId}/projects/{projectId}/... URIs. Authorization remains enforced by the Kernel API; selecting a project never grants access to it.

Inputs that mirror the API's nested proxy, network, browser, and proxy config objects replace older flat inputs such as proxy_id, proxy_routes, browser_region, and custom_host. The flat inputs remain as deprecated aliases, and combining one with its nested replacement is rejected. Tool-call analytics records the names, never the values, of deprecated inputs each call used in `$mcp_deprec