Frontal MCP Server

A standalone Model Context Protocol (MCP) server for the Frontal public API (api.frontal.dev). It exposes the API as a hybrid of curated, typed tools for the highest-value surfaces (ontology / knowledge graph and the data platform) plus spec-driven generic meta-tools that can reach any of the API's ~430 operations — all driven by the vendored OpenAPI spec.

Quick Start

Installation

# Install globally
npm install -g @frontal-labs/mcp-server

# Or install locally
npm install @frontal-labs/mcp-server

Basic Setup

1. Get your API key from Frontal Platform

2. Set up environment:

export FRONTAL_API_KEY="your_api_key_here"

3. Start the server:

# For Claude Desktop (stdio transport)
frontal-mcp-server --transport stdio

# For web applications (HTTP transport)
frontal-mcp-server --transport http --port 3000

Claude Desktop Integration

Add to your Claude Desktop configuration:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "frontal": {
      "command": "frontal-mcp-server",
      "args": ["--transport", "stdio"],
      "env": {
        "FRONTAL_API_KEY": "your_api_key_here"
      }
    }
  }
}

Related MCP server: poly-git-mcp

Features

• Full API coverage: Generic meta-tools drive any endpoint from the vendored OpenAPI spec (api.frontal.dev, ~430 operations).

• Curated tools: First-class, typed tools for the ontology / knowledge-graph and data-platform surfaces.

• Edge-aware client: Bearer frt_ auth, cursor pagination, 429/Retry-After backoff, the edge retry matrix (retry 429/502/503/504, never 401/409/501), idempotency keys on retried writes, and region pinning.

• Multi-transport: stdio (local / Claude Desktop) and Streamable HTTP, with per-request Authorization for multi-tenant hosting.

• Type safe: TypeScript throughout with Zod-validated tool inputs.

• Monitoring: Optional incident.io status-page integration and structured logging.

Available Tools

Tools are grouped into tool sets selectable via FRONTAL_TOOLSETS.

Generic (spec-driven) — generic

• frontal_list_endpoints: Browse the API surface, filtered by tag/search.

• frontal_describe_endpoint: Full parameter/body/response detail for one operation.

• frontal_call_endpoint: Invoke any operation by operationId (or method + path), with optional auto-pagination.

Ontology (curated) — ontology

ontology_list_objects, ontology_get_object, ontology_list_object_types, ontology_list_relationships, ontology_query_graph, ontology_graph_neighborhood, ontology_graph_path, ontology_extract_entities, ontology_list_schemas, ontology_get_schema.

Data platform (curated) — data

data_query_federated, data_list_datasets, data_get_dataset, data_list_pipelines, data_create_pipeline, data_get_pipeline, data_list_pipeline_runs, data_get_pipeline_run, data_ingest_dataset, data_list_streams, data_list_schemas.

Everything not covered by a curated tool stays reachable via the generic tools.

Configuration

Environment Variables

Over the HTTP transport, every MCP request must send a per-request Authorization: Bearer frt_... header (multi-tenant hosting); MCP requests without one are rejected with 401. The unauthenticated GET /health endpoint is the one exception: it always returns 200 {"status":"ok"} without a token. The FRONTAL_API_KEY env key is used only by the stdio transport and is never applied to HTTP requests. CORS trusts no origin by default: responses only carry Access-Control-Allow-Origin for origins listed in FRONTAL_HTTP_ALLOWED_ORIGINS (never *).

CLI Options

frontal-mcp-server [options]

Options:
  -t, --transport <type>     Transport type (stdio|http) [default: "stdio"]
  -p, --port <number>        HTTP port (for http transport) [default: 3000]
  -h, --host <address>       HTTP host (for http transport) [default: "localhost"]
  -k, --api-key <key>        Frontal API key
  -c, --config <path>         Configuration file path
  -v, --verbose              Verbose logging
  --log-level <level>        Log level (error|warn|info|debug) [default: "info"]

Usage Examples

Basic Usage

# Start with stdio transport (for Claude Desktop)
FRONTAL_API_KEY=your_key ./dist/bin/frontal-mcp-server.js

# Start with HTTP transport for web integration
FRONTAL_API_KEY=your_key ./dist/bin/frontal-mcp-server.js --transport http --port 3000

# Register only specific tool sets
FRONTAL_TOOLSETS=generic,data FRONTAL_API_KEY=your_key ./dist/bin/frontal-mcp-server.js

Programmatic Usage

import { FrontalMcpServer, createLogger } from '@frontal-labs/mcp-server';

import { createConfig } from '@frontal-labs/mcp-server';

const config = createConfig({
  apiKey: 'frt_your_api_key',
  toolsets: ['generic', 'ontology', 'data'],
  transport: { transport: 'stdio' },
});

const logger = createLogger({ level: 'info' });
const server = new FrontalMcpServer(config, logger);

await server.initialize();
await server.connectStdio();

Architecture

The server is a thin, spec-driven layer over the Frontal public API:

1. Vendored OpenAPI spec (openapi/public.v1.json) indexed at startup — the source of truth for endpoints, params, and auth.

2. Frontal client (src/clients/frontal-client.ts) — an edge-aware fetch client (auth, pagination, retry matrix, idempotency, region pin, errors).

3. Tool adapters — a generic (meta-tool) adapter plus curated ontology/data adapters, gated by FRONTAL_TOOLSETS.

4. Transport layer — stdio and Streamable HTTP, the latter binding a per-request bearer token via AsyncLocalStorage.

See ARCHITECTURE.md for details.

Development

Project Structure

mcp-server/
├── src/
│   ├── adapters/          # Service adapters for each Frontal service
│   ├── config/            # Configuration management
│   ├── server/            # Core MCP server implementation
│   ├── utils/             # Utilities (logging, etc.)
│   └── bin/               # CLI entry point
├── tests/                 # Test files
├── docs/                  # Documentation
└── examples/              # Integration examples

Scripts

# Build the project
bun run build

# Run tests
bun run test

# Run tests in watch mode
bun run test:watch

# Generate coverage report
bun run test:coverage

# Lint code
bun run lint

# Format code
bun run format

# Type check
bun run type-check

Current Status

Completed:

• Spec-driven integration against the real api.frontal.dev OpenAPI contract (vendored + refreshable via bun run sync-spec).

• Generic meta-tools (full coverage) + curated ontology/data tools.

• Edge-aware client (auth, pagination, retry matrix, idempotency, region pin).

• stdio and Streamable HTTP transports, per-request auth over HTTP.

• Test suite and CI (lint, type-check, coverage, build) plus Fly.io deploy.

Planned:

• Curated tools for more surfaces (events, webhooks, integrations, workflows, billing) — reachable today via the generic tools.

• MCP resources/prompts and optional OAuth flows.

Contributing

We welcome contributions! Please see our Developer Guide for detailed information.

1. Fork the repository

2. Create a feature branch

3. Make your changes

4. Run tests: bun run test

5. Submit a pull request

Documentation

• API Documentation - Complete API reference

• Usage Guide - Practical examples and integration patterns

• Developer Guide - Architecture and contribution guidelines

Troubleshooting

Common Issues

Server won't start:

# Check API key
echo $FRONTAL_API_KEY

# Validate configuration
frontal-mcp-server --validate-config

Connection issues:

# Test with different transport
frontal-mcp-server --transport http --port 3000

# Check logs
frontal-mcp-server --verbose

Performance issues:

# Enable debug logging
MCP_LOG_LEVEL=debug frontal-mcp-server

# Monitor resources
top -p $(pgrep frontal-mcp-server)

Getting Help

• GitHub Issues: Report bugs and request features

• Discord Community: Join our developer community

• Documentation: Check docs/ for detailed guides

License

Apache License 2.0 - see LICENSE file for details.