MCP turns the M×N integration explosion into M+N: each host speaks MCP once, each tool exposes MCP once, so they all interoperate without bespoke pairwise glue.
Picture a world before standard wall sockets, where every appliance needed its own custom plug for every house. A toaster wired for one home would not fit the next. If you had many homes and many appliances, you wired a unique connection for every single pair. That meant a huge number of one-off adapters. Then everyone agreed on one socket shape. Now each home installs that socket once, and each appliance ships one matching plug once. Any appliance works in any home. MCP is that shared socket for AI apps and tools. Each app learns to speak MCP a single time. Each tool exposes MCP a single time. Then every app can use every tool. No more hand-wiring a custom connector for each app and tool combination.
Concept explanation~2 min read
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Concept explanation~2 min read
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
The M×N integration problem is the single clearest way to explain why MCP exists. Strip away the protocol details and the argument is pure combinatorics. Suppose many applications each want to use many tools, and there is no shared standard. Then the integration work you must write grows as the product of the two counts. That product becomes unmanageable at scale. It is the reason the whole agent-tooling ecosystem felt stuck before a standard appeared.
The fix is to insert one shared interface between the two sides. Each side then builds against the interface once, not against every counterpart individually. It is a simple move, but it changes the scaling curve from a product into a sum. That is the economic reason MCP caught on so quickly.
The combinatorial blowup, derived
Start with the setup. You have M host applications, such as Claude Desktop, Cursor, an internal chatbot, or an IDE plug-in. You have N tools you want any of them to reach: a filesystem, a Postgres database, a GitHub connector, a Slack bridge.
Without a shared standard, integration is pairwise. Host 1 needs custom code to talk to tool 1, more custom code for tool 2, and so on through tool N. Repeat that for every host. The total number of bespoke adapters is the product:
The damage is not just the initial build. Every adapter is its own little project with its own authentication, its own schema mapping, and its own error handling. Add one new tool and you must touch all M hosts. Add one new host and it must integrate all N tools from scratch. The marginal cost of growth is itself proportional to the other dimension. That is why connector maintenance overwhelmed teams before a standard existed.
This is what the AI tooling landscape looked like in 2023 and early 2024. Every chatbot, IDE assistant, and agent framework shipped its own hand-written connectors for popular backends. A GitHub integration written for one assistant could not be reused by another, even though both were calling the same GitHub API for the same reasons. The work was duplicated across the industry, and every connector was a fresh surface for bugs, version drift, and security review. The pain was real and widely felt, and it created the need for a standard.
Situations where this technique stops working.
2–4 min · Everything important, quickly.
| Concern | No shared standard | With MCP |
|---|---|---|
| Integration count | M × N bespoke adapters | M + N (one per side) |
| Adding a new tool | Update every existing host | Ship one MCP server |
| Adding a new host | Re-integrate every tool | Implement one MCP client |
| Scaling behavior | Multiplicative, super-linear in practice | Linear in hosts plus tools |
| Tool reuse across apps | None; each pairing is custom | Write once, runs in any host |
Real products, models, and research that use this idea.
- Anthropic released MCP in November 2024 with official servers for filesystem, Postgres, Git, GitHub, and Slack as drop-in plug-ins.
- Zed supported MCP from launch in November 2024, and Cursor added it in early 2025. A server written for Claude Desktop runs unchanged in either editor.
What an interviewer would ask next. Try answering before peeking at the approach.
QWhy is the pre-standard cost often worse than a clean M×N would suggest?
Each adapter carries its own auth, schema mapping, and error handling. Tool upgrades force changes in every host that wired them, so maintenance makes the product term worse.
Red flags & common mistakes
The phrases that signal junior thinking. Click to expand.
Red flags & common mistakes
The phrases that signal junior thinking. Click to expand.
Saying MCP only saves a bit of code. The real win is collapsing combinatorial pairwise integrations into a linear count both sides build once.
60 second bullets to scan on the way to the call.
Why pairwise integration scales as a product of hosts and tools
How a shared protocol turns the product into a sum
Primary sources. Browse if you want the original framing.
Same topic, related formats. Practice these next.