An MCP Server is a lightweight program that exposes specific tools, resources, and prompts to AI clients via the 📝Model Context Protocol (MCP) standard, letting any compatible client invoke its capabilities without bespoke integration code.
MCP Servers solve the integration sprawl problem in AI tooling. Before MCP, every AI application needed bespoke connectors for every external system — a different SDK per database, per SaaS product, per knowledge base. An MCP Server publishes one standardized interface that any MCP-compatible client — 📝Claude Code, Claude.ai, 📝Cursor, Windsurf — can consume without custom integration code.
Each server exposes three primitive types: Tools the AI can invoke, Resources the AI can read, and Prompts that ship reusable instruction templates. Communication happens over two transport layers: stdio for local processes launched on the user's machine, and Streamable HTTP for remote services hosted as web endpoints.
The ecosystem has scaled rapidly since MCP's release. Public directories like mcp.so list 19,000+ servers as of April 2026 — filesystem and database connectors, browser automation via Playwright, Slack and GitHub integrations, and knowledge systems like 📝MythOS MCP. In Claude Code, MCP Servers are configured in ~/.claude/settings.json and become available as additional tools alongside the built-in toolset for the duration of the session.