What it does

A minimal, fetch-first MCP server implementation with zero runtime dependencies in its core. Unlike the official TypeScript SDK, mcp-lite is a ground-up rewrite that keeps only the essentials: JSON-RPC handling, typed tool definitions, and HTTP + SSE transport. It runs on Node.js, Bun, Cloudflare Workers, Deno, Supabase Edge Functions, and Service Workers, making it suitable for both traditional servers and serverless or edge environments.

Who it's for

Backend engineers and platform teams building MCP servers who want lightweight, dependency-free tooling. Ideal for teams deploying to serverless or edge environments where dependency count and bundle size matter, or those who prefer staying close to the MCP wire format without SDK overhead.

Common use cases

Deploy MCP servers to Cloudflare Workers or Supabase Edge Functions with minimal footprint
Define type-safe tools using Standard Schema validators (Zod, Valibot, Effect) with automatic TypeScript inference
Build multi-tool MCP servers with structured outputs and runtime validation
Scale from stateless prototypes to distributed deployments via pluggable session and storage adapters
Integrate MCP into existing HTTP frameworks (Hono, Express) without importing heavy SDK code

Setup pitfalls

The registry scanner found 3 secrets in the codebase—audit the source and any exposed credentials before using in production
Requires TypeScript or compilation to JavaScript; no browser-ready builds included
Adapters are opt-in but essential for production (sessions, persistence, client requests); stateless mode is development-only
Runtime environment varies significantly (Node.js, Cloudflare Workers, Deno, etc.)—consult examples for your target platform

Tool name

Description

Destructive?

test-tool

✓ no

echo

✓ no

slow-tool

✓ no

dynamic-tool

✓ no

auth-test

✓ no

no-auth-test		✓ no
middleware-test		✓ no
no-middleware-auth-test		✓ no
direct-auth-test		✓ no
direct-no-auth-test		✓ no
complex-auth-test		✓ no
consistency-test		✓ no
with-sampling		✓ no
no-sampling		✓ no
full-sampling		✓ no
image-sampling		✓ no
timeout-sampling		✓ no
invalid-response-sampling		✓ no
error-response-sampling		✓ no
sequential-sampling		✓ no
sampling-with-preferences		✓ no
test-capabilities		✓ no
search		✓ no
fileSearch		✓ no
calculate		✓ no
with-elicitation		✓ no
no-elicitation		✓ no
full-elicitation		✓ no
decline-elicitation		✓ no
cancel-elicitation		✓ no
timeout-elicitation		✓ no
invalid-response-elicitation		✓ no
error-response-elicitation		✓ no
sequential-elicitations		✓ no
empty-schema-elicitation		✓ no
optional-fields-elicitation		✓ no
double		✓ no
calculateSum		✓ no
getWeather		✓ no
ping		✓ no
experimental-feature		✓ no
getConfig		✓ no
deleteDatabase⚠		⚠ yes