frontmcp-config

Agent Building

Use when configuring a FrontMCP server through frontmcp.config or the @FrontMcp options. Covers auth modes (public, transparent, local, remote), OAuth plus credential vault and secureStore, CORS, HTTP port / entry-path prefix / unix socket, security headers (CSP, HSTS, X-Frame-Options, X-Content-Type-Options), rate limiting / throttling / concurrency / timeout / IP filtering (GuardConfig), session storage (Redis, Vercel KV), client transport protocols (SSE, Streamable HTTP, stateless, protocol presets), elicitation, multi-target build config, and skillsConfig (HTTP catalog, caching, audit log, instruction injection). Triggers: configure auth, set up CORS, add rate limiting, throttle requests, manage sessions, choose transport, set HTTP options, configure JWT or OAuth. The skill for server CONFIGURATION.

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Source SKILL.md: https://github.com/agentfront/frontmcp/blob/HEAD/libs/skills/catalog/frontmcp-config/SKILL.md

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FrontMCP Configuration Router

Entry point for configuring FrontMCP servers. This skill helps you find the right configuration reference (under references/) based on what aspect of your server you need to set up.

When to Use This Skill

Must Use

Setting up a new server and need to understand which configuration options exist
Deciding between authentication modes, transport protocols, or storage backends
Planning server configuration across transport, auth, throttling, and storage

Skip When

You already know which config area to change (go directly to configure-transport, configure-auth, etc.)
You need to build components, not configure the server (see frontmcp-development)
You need to deploy, not configure (see frontmcp-deployment)

Decision: Use this skill when you need to figure out WHAT to configure. Open the matching reference under references/ directly when you already know.

Prerequisites

A FrontMCP project scaffolded with frontmcp create (see frontmcp-setup)
Node.js 24+ and npm/yarn installed

Steps

Identify the configuration area you need using the Scenario Routing Table below
Navigate to the specific configuration reference (e.g., references/configure-transport.md, references/configure-auth.md) for detailed instructions
Apply the configuration in your @FrontMcp or @App decorator
Verify using the Verification Checklist at the end of this skill

Scenario Routing Table

Scenario	Reference	Description
Choose between SSE, Streamable HTTP, or stdio	`configure-transport`	Transport protocol selection with distributed session options
Set up CORS, port, base path, or request limits	`configure-http`	HTTP server options for Streamable HTTP and SSE transports
Add rate limiting, concurrency, or IP filtering	`configure-throttle`	Server-level and per-tool throttle configuration
Enable tools to ask users for input	`configure-elicitation`	Elicitation schemas, stores, and multi-step flows
Set up authentication (public, transparent, local, remote)	`configure-auth`	OAuth flows, credential vault, multi-app auth
Configure session storage backends	`configure-session`	Memory, Redis, Vercel KV, and custom session stores
Add Redis for production storage	`setup-redis`	Docker Redis, Vercel KV, pub/sub for distributed subscriptions
Add SQLite for local development	`setup-sqlite`	SQLite with WAL mode, migration helpers
Understand auth mode details (public/transparent/local/remote)	`configure-auth-modes`	Authentication mode details (public, transparent, local, remote)
Fine-tune guard configuration for throttling	`configure-throttle-guard-config`	Advanced guard configuration for throttling
Use transport protocol presets	`configure-transport-protocol-presets`	Transport protocol preset configurations
Configure multi-target deployments and frontmcp.config.ts	`configure-deployment-targets`	Typed config with defineConfig(), 9 deployment targets, JSON schema
Add CSP, HSTS, X-Frame-Options, and other security headers	`configure-security-headers`	CSP directives, report-only mode, HSTS preload, custom headers
Configure skills HTTP, instructions injection, or audit log	`configure-skills-http`	Full `skillsConfig` reference: auth, cache, instructions, audit log
Split apps into separate scopes (`splitByApp`)	`decorators-guide`	Per-app scope and basePath isolation on `@FrontMcp`
Enable widget-to-host communication (ext-apps)	`decorators-guide`	`extApps` host capabilities, session validation, widget comms
Enable background jobs and workflows	`decorators-guide`	`jobs: { enabled: true, store? }` on `@FrontMcp`
Configure pagination for list operations	`decorators-guide`	`pagination` defaults for `tools/list` endpoint
Configure npm/ESM package loader for remote apps	`decorators-guide`	`loader` config for `App.esm()` / `App.remote()` resolution

Configuration Layers

FrontMCP configuration cascades through three layers:

Server (@FrontMcp)     ← Global defaults
  └── App (@App)       ← App-level overrides
       └── Tool (@Tool) ← Per-tool overrides

Setting	Server (`@FrontMcp`)	App (`@App`)	Tool (`@Tool`)
Transport	Yes	No	No
HTTP (CORS, port)	Yes	No	No
Throttle (rate limit)	Yes (`throttle` global defaults)	No	Yes (`rateLimit`, `concurrency`, `timeout`)
Auth mode	Yes	Yes (override)	No
Auth providers	No	Yes (`authProviders`)	Yes (`authProviders`)
Session store	Yes	No	No
Elicitation	Yes (enable: `elicitation`)	No	Yes (usage: `this.elicit()`)
ExtApps	Yes	No	No
Jobs / Workflows	Yes (`jobs: { enabled }`)	No	No
Pagination	Yes	No	No
SplitByApp	Yes	No	No

Cross-Cutting Patterns

Pattern	Rule
Auth + session	Auth mode determines session requirements: `remote` needs Redis/KV; `public` can use memory
Transport + storage	Stateless transports (serverless) require distributed storage; stateful (Node) can use in-process
Throttle scope	Server-level throttle applies to all tools; per-tool throttle overrides for specific tools
Environment config	Use environment variables for all secrets (API keys, Redis URLs, OAuth credentials)
Config validation	FrontMCP validates config at startup; invalid config throws before the server starts

Common Patterns

Pattern	Correct	Incorrect	Why
Auth mode for dev	`auth: { mode: 'public' }` or `auth: { mode: 'transparent', provider: '...' }` locally	`auth: { mode: 'remote', ... }` with real OAuth in dev	Remote auth requires a running OAuth provider; public/transparent are simpler for local dev
Session store	Redis for production, memory for development	Memory for production	Memory sessions are lost on restart and don't work across serverless invocations
Rate limit placement	Server-level for global limits, per-tool for expensive operations	Only server-level	Some tools are cheap (list) and some are expensive (generate); per-tool limits prevent abuse of expensive tools
CORS config	Explicit allowed origins in production	`cors: { origin: '*' }` in production	Wildcard CORS allows any origin to call your server
Config secrets	`process.env.REDIS_URL` via environment variable	Hardcoded `redis://localhost:6379` in source	Hardcoded secrets leak to git and break in different environments

Verification Checklist

Transport and HTTP

Transport protocol configured and server starts without errors
CORS allows expected origins (test with browser or curl)
Port and base path accessible from client

Authentication

Auth mode set appropriately for the environment (public/transparent for dev, remote for prod)
OAuth credentials stored in environment variables, not source code
Session store configured with appropriate backend (memory for dev, Redis for prod)

Throttle and Security

Global rate limit configured to prevent abuse
Expensive tools have per-tool throttle overrides
IP allow/deny lists configured if needed

Storage

Redis or SQLite configured and connectable
Storage persists across server restarts (not memory in production)

Troubleshooting

Problem	Cause	Solution
Server fails to start with config error	Invalid or missing required config field	Check the error message; FrontMCP validates config at startup and reports the specific invalid field
CORS blocked in browser	Missing or incorrect CORS origin config	Add the client's origin to `http.cors.origin`; see `configure-http`
Rate limit too aggressive	Global limit applied to all tools	Add per-tool overrides for cheap tools with higher limits; see `configure-throttle`
Sessions lost on serverless	Using memory session store on stateless platform	Switch to Redis or Vercel KV; see `configure-session`
Auth callback fails	OAuth redirect URI mismatch	Ensure the redirect URI registered with your OAuth provider matches the server's `/oauth/callback` endpoint; see `configure-auth`

Examples

Each reference has matching examples under examples/<reference>/:

`configure-auth-modes`

Example	Level	Description
`local-self-signed-tokens`	Intermediate	Configure a server that signs its own JWT tokens with consent and incremental auth enabled.
`remote-enterprise-oauth`	Advanced	Proxy auth to one mandatory upstream IdP, mint a FrontMCP session, read the upstream token.
`transparent-jwt-validation`	Basic	Validate externally-issued JWTs without managing token lifecycle on the server.

`configure-auth`

Example	Level	Description
`multi-app-auth`	Advanced	Configure a single FrontMCP server with multiple apps, each using a different auth mode -- public for open endpoints and remote for admin endpoints.
`public-mode-setup`	Basic	Set up a FrontMCP server with public (unauthenticated) access and anonymous scopes.
`remote-oauth-with-vault`	Intermediate	Configure a FrontMCP server with remote OAuth 2.1 authentication and use the credential vault to call downstream APIs on behalf of the authenticated user.

`configure-elicitation`

Example	Level	Description
`basic-confirmation-gate`	Basic	Request user confirmation before executing a destructive action.
`distributed-elicitation-redis`	Intermediate	Configure elicitation with Redis storage for multi-instance production deployments.

`configure-http`

Example	Level	Description
`cors-restricted-origins`	Basic	Configure CORS to allow only specific frontend origins with credentials.
`entry-path-reverse-proxy`	Intermediate	Mount the MCP server under a URL prefix for reverse proxy or multi-service setups.
`unix-socket-local`	Intermediate	Bind the server to a unix socket instead of a TCP port for local-only communication.

`configure-session`

Example	Level	Description
`multi-server-key-prefix`	Intermediate	Use unique key prefixes when multiple FrontMCP servers share one Redis instance.
`redis-session-store`	Basic	Configure Redis-backed session storage for production deployments.
`vercel-kv-session`	Intermediate	Configure Vercel KV for session storage in serverless Vercel deployments.

`configure-throttle-guard-config`

Example	Level	Description
`full-guard-config`	Advanced	Complete GuardConfig using every available field for maximum protection.
`minimal-guard-config`	Basic	Enable throttle with just a global rate limit and default timeout.

`configure-throttle`

Example	Level	Description
`distributed-redis-throttle`	Advanced	Configure Redis-backed rate limiting for multi-instance deployments behind a load balancer.
`per-tool-rate-limit`	Intermediate	Override server defaults with per-tool rate limits and concurrency caps.
`server-level-rate-limit`	Basic	Configure global rate limits and IP filtering at the server level.

`configure-transport-protocol-presets`

Example	Level	Description
`legacy-preset-nodejs`	Basic	Use the default legacy preset for maximum compatibility with all MCP clients.
`stateless-api-serverless`	Intermediate	Use the stateless-api preset for Vercel, Lambda, or Cloudflare Workers.

`configure-transport`

Example	Level	Description
`custom-protocol-flags`	Advanced	Override individual protocol flags instead of using a preset for fine-grained control.
`distributed-sessions-redis`	Intermediate	Configure transport with Redis persistence for multi-instance load-balanced deployments.
`stateless-serverless`	Basic	Configure stateless transport for Vercel, Lambda, or Cloudflare deployments.

`configure-deployment-targets`

Example	Level	Description
`multi-target-with-security`	Intermediate	Configure a FrontMCP project with node + distributed targets, CSP headers, and HSTS
`distributed-ha-config`	Advanced	Configure a distributed deployment target with HA settings for heartbeat, session takeover, and Redis-backed session persistence
`json-schema-ide-support`	Basic	Use frontmcp.config.json with JSON Schema for VS Code and WebStorm autocomplete

`configure-security-headers`

Example	Level	Description
`csp-report-only`	Basic	Test CSP policies in report-only mode to identify violations before enforcement
`full-production-headers`	Intermediate	Complete security headers configuration for production with CSP enforcement, HSTS preload, and clickjacking protection

Accessing This Skill

Skills are distributed as plain SKILL.md files plus a sibling references/ and examples/ tree, so consumers can pick whichever access mode fits:

Mode	How it works
Filesystem	Read `libs/skills/catalog/frontmcp-config/` directly from a clone of the catalog repo, or from a published `@frontmcp/skills` install. SKILL.md is the entry point.
`frontmcp` CLI	`frontmcp skills list`, `frontmcp skills read frontmcp-config`, `frontmcp skills read frontmcp-config:references/<file>.md`, `frontmcp skills install frontmcp-config` — no server required.
MCP `skill://`	When a developer mounts this skill into their own FrontMCP server (`@FrontMcp({ skills: [...] })`), the SDK exposes it via SEP-2640 resources: `skill://frontmcp-config/SKILL.md`, `skill://frontmcp-config/references/{file}.md`, etc. The server’s `skill://index.json` returns the SEP-2640 discovery document for everything mounted on it.

The catalog itself is not an MCP server. The skill:// URIs only resolve when a server has been configured to host this skill.

Reference

FrontMCP Overview
Related skills: configure-transport, configure-http, configure-throttle, configure-elicitation, configure-auth, configure-session, setup-redis, setup-sqlite