MCP (Model Context Protocol) is an open standard for connecting AI applications to external systems. The official documentation describes it as a USB-C-like standard connection for AI applications.[1] The reason MCP is necessary lies in the M×N integration problem. As the number of AI applications (M) and external tools (N) grows, the amount of custom integration code multiplies, making the system hard to scale. MCP reduces this to M+N.
The M×N Integration Problem
A World Without MCP
Without MCP, each AI application must implement dedicated code for every tool it wants to connect to.
Consider a scenario with three AI apps and three tools:
AI App 1 → custom code for Database
AI App 1 → custom code for File System
AI App 1 → custom code for Calculator API
AI App 2 → custom code for Database (separate implementation)
AI App 2 → custom code for File System (separate implementation)
AI App 2 → custom code for Calculator API (separate implementation)
AI App 3 → ... (same, three more)Three apps × three tools = 9 separate integrations required.
graph LR
subgraph "Without MCP (M×N = 9 integrations)"
A1[AI App 1] -->|custom code| T1[(Database)]
A1 -->|custom code| T2[File\nSystem]
A1 -->|custom code| T3[Calculator API]
A2[AI App 2] -->|custom code| T1
A2 -->|custom code| T2
A2 -->|custom code| T3
A3[AI App 3] -->|custom code| T1
A3 -->|custom code| T2
A3 -->|custom code| T3
endWhy the Problem Gets Worse
This structure has the following issues:
| Problem | Description |
|---|---|
| Exploding development costs | Integration code grows multiplicatively as M and N increase |
| Maintenance difficulty | When a tool’s API changes, every AI app using it must be updated |
| Inconsistent quality | Each team implements independently, leading to varied error handling and security |
| Burden on tool providers | Must provide separate SDKs or plugins for each AI platform |
In practice, the official MCP documentation already lists support examples such as Claude, ChatGPT, Visual Studio Code, and Cursor.[1] Tool-side integrations also span files, databases, search, and workflows, so pairwise custom integration grows quickly.
Understanding the M×N Problem With Real Services
Abstract explanations can be hard to grasp, so let me use real service names to make this concrete.
A Concrete Scenario
3 AI apps: Claude Desktop, Cursor, Windsurf 3 external tools: GitHub, Slack, Figma
Without MCP, here is what the integration table looks like:
| AI App | GitHub Integration | Slack Integration | Figma Integration |
|---|---|---|---|
| Claude Desktop | Custom impl. A | Custom impl. B | Custom impl. C |
| Cursor | Custom impl. D | Custom impl. E | Custom impl. F |
| Windsurf | Custom impl. G | Custom impl. H | Custom impl. I |
3 × 3 = 9 separate pieces of “glue code” are needed. This number is a simple explanatory calculation that assumes each app connects separately to each tool.
And if GitHub updates its API, I have to fix custom implementations A, D, and G — all three, separately.
With MCP
The same scenario with MCP:
- GitHub publishes one GitHub MCP server
- Slack publishes one Slack MCP server
- Figma publishes one Figma MCP server
- Claude Desktop, Cursor, and Windsurf each implement one MCP client
Total: 3 (AI apps) + 3 (tools) = just 6 implementations.
If GitHub updates its API, only one place needs updating — the GitHub MCP server.
The Difference Grows With Scale
| Scale | Without MCP | With MCP | Reduction |
|---|---|---|---|
| 3 apps × 3 tools | 9 | 6 (3+3) | 33% |
| 10 apps × 20 tools | 200 | 30 (10+20) | 85% |
| 100 apps × 100 tools | 10,000 | 200 (100+100) | 98% |
The more apps and tools there are, the greater the effect of moving from pairwise integrations to a shared protocol.
The MCP Solution: M+N
A World With MCP
Introducing MCP fundamentally changes the structure:
- Each AI app implements an “MCP client” exactly once
- Each tool implements an “MCP server” exactly once
- Because they speak a common protocol (MCP), no custom code is needed for new combinations
graph LR
subgraph "With MCP (M+N = only 6 implementations)"
A1[AI App 1\nMCP Client] --> MCP{MCP\nProtocol}
A2[AI App 2\nMCP Client] --> MCP
A3[AI App 3\nMCP Client] --> MCP
MCP --> T1[(Database\nMCP Server)]
MCP --> T2[File System\nMCP Server]
MCP --> T3[Calculator API\nMCP Server]
endComparing the Reduction
| Scenario | Without MCP | With MCP |
|---|---|---|
| 3 apps × 3 tools | 9 integrations | 6 (3+3) |
| 10 apps × 20 tools | 200 integrations | 30 (10+20) |
| 100 apps × 100 tools | 10,000 integrations | 200 (100+100) |
| Impact of a tool’s API change | All AI apps affected | Only 1 MCP server needs updating |
The more apps and tools there are, the greater MCP’s impact.
Real-World Benefits
For AI App Developers
Once I implement an MCP client, I can connect to MCP-compatible servers through the shared protocol.[2] When new tools appear, I reduce the amount of per-API integration code I need to write.
For Tool Providers
Once I publish an MCP server, MCP-compatible clients can use it through the same protocol.[2] I no longer need to duplicate as many custom integrations for specific AI platforms.
For End Users
When I switch AI apps, I can continue using the same tools without any changes. The freedom to combine tools and apps increases significantly.
Summary
- Without MCP, integrating M AI apps with N tools requires M×N implementations
- With MCP, each side implements once, reducing the total to M+N
- The more apps and tools that exist, the more dramatic this reduction becomes
Frequently Asked Questions
Q: How was the M×N problem solved before MCP existed?
A: Each AI provider offered its own plugin system (e.g., OpenAI Plugins, LangChain’s tool functionality). However, these were not standardized, so a plugin built for one AI app could not be reused in another. MCP aims to solve this problem as an industry-wide common standard.
Q: How is MCP different from frameworks like LangChain or LlamaIndex?
A: LangChain and LlamaIndex are frameworks written in specific programming languages (primarily Python/TypeScript) — libraries for building AI applications. MCP is a language-agnostic protocol (communication standard). It is entirely possible to combine them: a LangChain app implementing an MCP client and communicating with MCP servers.
Q: Does every AI app support MCP?
A: The official MCP documentation lists support examples including Claude, ChatGPT, Visual Studio Code, and Cursor.[1] However, not every AI app supports MCP, so check the current documentation for the app you plan to use.
Related Links
- What is MCP? — Basic MCP concepts
- MCP Architecture — Host, Client, and Server roles
References
- Model Context Protocol, What is the Model Context Protocol?
- Model Context Protocol, Architecture overview