Best Middleware AI Skills & MCP Servers

Hardened, self-hosted Excalidraw MCP server with SQLite persistence, multi-tenancy, auto-sync, security middleware, and 369 tests

L402 Lightning paywall + Depth-of-Identity score gate for MCP. Two integration shapes: (a) stdio MCP server exposing l402_gate_challenge / l402_gate_verify / l402_gate_score for agent clients; (b) drop-in Express middleware + MCP tool factory that combine

AINative ZeroDB Memory MCP Server - 18 tools for agent memory: 9 memory + 5 write-back (Slack, Gmail, Calendar, GitHub, Notion) + 4 plan artifacts (persistent plans/PRDs across sessions with diff history). Auto-context middleware. Production-ready for Cla

MVA (Model-View-Agent) framework for the Model Context Protocol. Structured perception packages with Presenters, cognitive guardrails, self-healing errors, action consolidation, and tRPC-style type safety — so AI agents perceive and act on your data deter

Express middleware for handling Model Context Protocol (MCP) requests

A Model Context Protocol (MCP) server that acts as a passthrough proxy with hook middleware support

Generic config-driven MCP wrapper for atrib. Spawns any upstream MCP server and applies @atrib/mcp middleware so every tool call is signed and logged. Wrap any MCP via JSON config, no per-server code.

Agent middleware for atrib. Interceptor plus framework adapters for MCP attribution. Supports raw SDK, Claude Agent SDK, Cloudflare Agents, Vercel AI SDK, LangChain JS.

Express middleware library for MCP (Model Context Protocol) OAuth authentication

MCP server middleware for atrib. Signed receipts for every tool call, one-line integration.

FDKEY verification middleware for MCP servers — gate AI-agent access behind LLM-only puzzles. Runs on Node 18+, Cloudflare Workers, Bun, and Deno.