The Complete Guide to MCP Servers: Connecting AI Agents to GitHub, Slack, Notion, and More

If you've searched for github mcp, slack mcp, notion mcp, or any of a dozen other "[tool] mcp" queries lately, you're not alone MCP has become the default way agents talk to the apps people actually use. But most explanations either stay too abstract ("MCP is a protocol for tool use") or too narrow (a single-server tutorial). Here's the practical version: what MCP servers actually do, which ones matter most right now, and how to pick between building your own and using an existing one.

What an MCP server actually does

MCP (Model Context Protocol) standardizes how an AI agent discovers and calls external tools. Instead of every product inventing its own function calling schema, an MCP server exposes a set of typed methods "search files," "send message," "create issue" that any MCP compatible agent (Claude, and a growing list of others) can call the same way.

Practically, this means a github mcp server exposes methods like "list open PRs" or "create an issue," a slack mcp server exposes "post message" or "read channel history," and so on. The agent doesn't need custom integration code per provider it needs one MCP client, and the server on the other end handles auth, rate limits, and the provider's actual API.

The MCP servers developers ask about most

Based on how people are actually searching, a handful of integrations dominate:

• GitHub MCP / GitHub MCP server — issues, PRs, repo search, commit history. The most-requested integration for coding agents specifically.
• Slack MCP server — reading and posting messages, which pairs naturally with notification and triage workflows.
• Notion MCP / Notion MCP server — reading and writing pages, useful for agents that manage docs or knowledge bases.
• Figma MCP / Figma MCP server — pulling design context (frames, components, styles) into a coding agent, a fast-growing category on its own.
• Linear MCP server — issue tracking for teams that live in Linear instead of Jira or GitHub Issues.
• Supabase MCP and Stripe MCP — database and payments access, respectively, for agents that need to query data or handle transactions.
• Cursor MCP and Claude Code MCP — not integrations themselves, but the editors and CLI tools that consume MCP servers, which is why "claude code mcp server setup" and "cursor mcp servers" show up constantly in search.

Claude Code MCP setup, briefly

A recurring question is simply: how do I add an MCP server to Claude Code? The short version Claude Code reads a .mcp.json configuration (project-level or user-level) that lists each MCP server's URL or launch command. Once added, the tools that server exposes show up automatically in Claude Code's tool list, no separate integration work required per project. The same pattern holds for Cursor: MCP servers are added once, in configuration, and then available across every session.

Building an AI agent builder vs. wiring up MCP servers

There's a real distinction between an AI agent builder the framework or platform that defines an agent's reasoning loop, memory, and orchestration and the MCP servers that give that agent hands. You can have the best agent loop in the world; if it can't reliably call GitHub, Slack, and Notion without the token expiring or the schema silently changing, none of that reasoning matters in production.

This is why teams building AI agent tools increasingly treat MCP servers as infrastructure to source, not build from scratch per integration. The pattern that keeps showing up in the highest-volume searches — "github mcp," "slack mcp," "notion mcp," "figma mcp," "supabase mcp" — is a signal that developers want these as a library of pre-built, typed connections, not a fresh OAuth implementation every time.

What to actually check before adopting an MCP server

• Is it open source? A closed-source MCP server means you're stuck waiting on the vendor's roadmap if you need a method they haven't built yet.
• Does it handle multi-tenancy? If you're building a product with more than one customer, "one API key in an env variable" doesn't scale you need per-tenant credential isolation.
• What's the permission model? Read access and write access (sending a message, merging a PR, deleting a file) are very different risk profiles. A good MCP server lets you gate the second category behind explicit approval.
• How is caching handled? Repeated reads shouldn't mean repeated calls to the underlying API good servers cache and refresh via webhooks, not brute-force polling.

Corsair as an MCP layer

Corsair is an open-source integration layer that ships GitHub, Slack, Notion, Linear, Stripe, Airtable, Google Calendar, and more as MCP-ready plugins, with multi-tenant OAuth, permission gates, and envelope-encrypted credentials built in from the start. Drop a Corsair MCP URL into Claude, Cursor, or Claude Code, and every connected plugin becomes available immediately no separate OAuth flow to write per integration. Prefer to own the stack? npm install corsair runs the same plugins self-hosted, for free, on your own infrastructure. And because it's open source, an MCP server you need but don't see yet is a PR away, not a feature request into the void.

Star Corsair on GitHub → · Read the docs →

FAQs

What's the difference between an MCP server and an API integration? An API integration is typically custom code your team writes to call one provider's API. An MCP server standardizes that connection behind a common protocol, so any MCP-compatible agent can call it the same way no custom glue code per tool.

Do I need a different MCP client for GitHub versus Slack versus Notion? No. The client (Claude, Claude Code, Cursor) speaks MCP once. Each server GitHub, Slack, Notion, etc. exposes its own methods, but the agent calls all of them through the same protocol.

How do I add an MCP server to Claude Code? You add it to Claude Code's MCP configuration (.mcp.json) with the server's URL or launch command. Once added, its tools appear automatically in that project's tool list.

Is it safe to use a third-party MCP server with production data? It depends entirely on the server's security model look for multi-tenant credential isolation, encrypted credential storage, and permission gates on write actions before connecting it to real customer data.

Should I build my own MCP server or use an existing open-source one? If a well-maintained, open-source MCP server already covers the integration you need, using it saves weeks of OAuth, rate-limiting, and caching work. Build your own only when your integration is genuinely proprietary or unsupported anywhere.