looker-mcp-server 0.1.2

A Model Context Protocol (MCP) server for the Looker API with full tool coverage, OAuth pass-through, and user impersonation support.

looker-mcp-server

A full-featured Model Context Protocol (MCP) server for the Looker API. Gives AI assistants direct access to your Looker instance — querying the semantic model, managing content, editing LookML, and administering users — all through a standard MCP interface.

Features

• 56 tools across 8 groups covering the full Looker API surface
• Semantic layer queries — query through LookML models, not raw SQL
• OAuth pass-through — forward user tokens from an upstream gateway or MCP OAuth flow
• User impersonation — admin sudo on self-hosted Looker, OAuth on Google Cloud core
• Dual transport — stdio for local/CLI use, streamable-http for production deployment
• Selective tool loading — enable only the tool groups you need via --groups
• Pluggable identity — swap in custom authentication via the IdentityProvider protocol
• Health endpoints — /healthz and /readyz for container orchestration

Quick Start

Installation

pip install looker-mcp-server
# or
uv add looker-mcp-server

Environment Variables

At minimum, set your Looker instance URL and API3 credentials:

export LOOKER_BASE_URL="https://mycompany.looker.com"
export LOOKER_CLIENT_ID="your-api3-client-id"
export LOOKER_CLIENT_SECRET="your-api3-client-secret"

Run with stdio (for Claude Code, Claude Desktop, etc.)

looker-mcp-server --groups explore,query,schema

Run with HTTP (for production deployment)

LOOKER_TRANSPORT=streamable-http looker-mcp-server --groups all --port 8080

MCP Client Configuration

Claude Code

Add to your Claude Code MCP settings:

{
  "mcpServers": {
    "looker": {
      "command": "looker-mcp-server",
      "args": ["--groups", "explore,query,schema,content"],
      "env": {
        "LOOKER_BASE_URL": "https://mycompany.looker.com",
        "LOOKER_CLIENT_ID": "your-client-id",
        "LOOKER_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "looker": {
      "command": "looker-mcp-server",
      "args": ["--groups", "explore,query,schema,content"],
      "env": {
        "LOOKER_BASE_URL": "https://mycompany.looker.com",
        "LOOKER_CLIENT_ID": "your-client-id",
        "LOOKER_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

Tool Groups

Tools are organized into groups that can be selectively enabled. Default groups are marked with *.

Group	Tools	Description
explore*	list_models, get_model, get_explore, list_dimensions, list_measures, list_connections	Browse LookML models, explores, and fields
query*	query, query_sql, run_look, run_dashboard, query_url, search_content	Run queries through the semantic layer
schema*	list_databases, list_schemas, list_tables, list_columns	Inspect underlying database schema
content*	list_looks, create_look, update_look, delete_look, list_dashboards, create_dashboard, update_dashboard, delete_dashboard, add_dashboard_element, add_dashboard_filter, generate_embed_url	Manage Looks and dashboards
health*	health_pulse, health_analyze, health_vacuum	Instance health checks and usage analysis
modeling	list_projects, list_project_files, get_file, create_file, update_file, delete_file, validate_project	Edit LookML files and validate syntax
git	get_git_branch, list_git_branches, create_git_branch, switch_git_branch, deploy_to_production, reset_to_production	Git operations and production deployment
admin	list_users, get_user, create_user, update_user, delete_user, list_roles, create_role, list_groups, add_group_user, remove_group_user, list_schedules, create_schedule, delete_schedule	User, role, group, and schedule management

Selecting Groups

# Default groups only (explore, query, schema, content, health)
looker-mcp-server

# Specific groups
looker-mcp-server --groups explore,query

# All groups (including modeling, git, admin)
looker-mcp-server --groups all

Configuration Reference

All settings are configured via environment variables with the LOOKER_ prefix, or via a .env file.

Variable	Default	Description
LOOKER_BASE_URL	(required)	Base URL of the Looker instance
LOOKER_CLIENT_ID		API3 client ID for service account
LOOKER_CLIENT_SECRET		API3 client secret for service account
LOOKER_API_VERSION	4.0	Looker API version
LOOKER_DEPLOYMENT_TYPE	self_hosted	self_hosted or google_cloud_core
LOOKER_TRANSPORT	stdio	stdio or streamable-http
LOOKER_HOST	0.0.0.0	HTTP bind address
LOOKER_PORT	8080	HTTP port
LOOKER_SUDO_AS_USER	true	Enable user impersonation when identity headers are present
LOOKER_SUDO_ASSOCIATIVE	false	Attribute sudo activity to admin (true) or impersonated user (false)
LOOKER_USER_EMAIL_HEADER	X-User-Email	HTTP header carrying user email for sudo impersonation
LOOKER_USER_TOKEN_HEADER	X-User-Token	HTTP header carrying pre-exchanged OAuth token
LOOKER_TIMEOUT	60.0	HTTP request timeout in seconds
LOOKER_MAX_ROWS	5000	Default maximum rows for query tools
LOOKER_VERIFY_SSL	true	Verify TLS certificates
LOOKER_LOG_LEVEL	INFO	Logging level
LOOKER_MCP_AUTH_TOKEN		Static bearer token for MCP-level authentication

Authentication & Impersonation

The server supports three authentication modes, selected automatically based on configuration and request headers.

Mode 1: Service Account (API Key)

The simplest mode — all API calls use the configured service-account credentials.

export LOOKER_CLIENT_ID="your-api3-client-id"
export LOOKER_CLIENT_SECRET="your-api3-client-secret"
export LOOKER_SUDO_AS_USER=false

Mode 2: Admin Sudo (Self-Hosted Looker)

An admin service account impersonates individual users via Looker's login_user API. The user is identified by an email address in the request headers (typically set by an upstream gateway).

export LOOKER_CLIENT_ID="admin-api3-client-id"
export LOOKER_CLIENT_SECRET="admin-api3-client-secret"
export LOOKER_DEPLOYMENT_TYPE=self_hosted
export LOOKER_SUDO_AS_USER=true

When a request arrives with X-User-Email: [e-mail], the server:

1. Logs in with admin credentials
2. Looks up Alice's Looker user ID by email
3. Creates a sudo session as Alice via login_user
4. Executes the tool call as Alice
5. Logs out both sessions

Note: On Looker (Google Cloud core), login_user only works for Embed-type users. Regular users require OAuth mode.

Mode 3: OAuth Pass-Through (Google Cloud Core)

For Looker (Google Cloud core) deployments where regular users cannot be impersonated via sudo. An upstream gateway performs OAuth token exchange and passes the user's token in a header.

export LOOKER_CLIENT_ID="fallback-api3-client-id"
export LOOKER_CLIENT_SECRET="fallback-api3-client-secret"
export LOOKER_DEPLOYMENT_TYPE=google_cloud_core
export LOOKER_SUDO_AS_USER=true

When a request arrives with X-User-Token: <oauth-access-token>, the server uses that token directly — no login/logout cycle needed.

If no token header is present, the server falls back to service-account mode.

Automatic Mode Selection

When LOOKER_SUDO_AS_USER=true (the default), the server uses a DualModeIdentityProvider that automatically routes:

• Self-hosted → sudo (via X-User-Email header)
• Google Cloud core → OAuth (via X-User-Token header)
• No identity headers → service account fallback

Extending with Custom Identity Providers

The IdentityProvider protocol is the primary extension point for integrating with custom authentication systems.

from looker_mcp_server.identity import IdentityProvider, LookerIdentity, RequestContext
from looker_mcp_server.server import create_server
from looker_mcp_server.config import LookerConfig


class MyIdentityProvider:
    """Custom identity provider that integrates with your auth system."""

    async def resolve(self, context: RequestContext) -> LookerIdentity:
        # Extract identity from headers, tokens, etc.
        token = context.headers.get("authorization", "").removeprefix("Bearer ")

        if token:
            # Exchange for a Looker-scoped token via your auth system
            looker_token = await my_token_exchange(token)
            return LookerIdentity(mode="oauth", access_token=looker_token)

        # Fall back to service account
        return LookerIdentity(
            mode="api_key",
            client_id="your-client-id",
            client_secret="your-client-secret",
        )


# Wire it up
config = LookerConfig()
mcp, client = create_server(config, identity_provider=MyIdentityProvider())

The RequestContext provides:

• headers — HTTP request headers (empty in stdio mode)
• tool_name — name of the MCP tool being invoked
• tool_group — which group the tool belongs to
• arguments — arguments passed to the tool

MCP-Level Authentication

To protect the MCP server itself (who can connect to it), set a static bearer token:

export LOOKER_MCP_AUTH_TOKEN="your-secret-mcp-token"

MCP clients must then include this token in their connection. This is separate from Looker API authentication.

Health Endpoints

When running in HTTP mode, the server exposes:

• GET /healthz — liveness probe (always returns 200 if server is running)
• GET /readyz — readiness probe (verifies Looker connectivity with a login/logout cycle)

Development

# Clone
git clone https://github.com/ultrathink-solutions/looker-mcp-server.git
cd looker-mcp-server

# Install dependencies
uv sync --locked --dev

# Run quality checks
uv run ruff check .        # lint
uv run ruff format .       # format
uv run pyright             # type check
uv run pytest tests/ -v    # tests

See CONTRIBUTING.md for contribution guidelines.

License

Apache License 2.0