BLUF
Problem: Claude makes wrong assumptions about library APIs from outdated training data.
Solution: Context7 MCP server loads live documentation directly into Claude’s context.
Setup:
- Install:
claude mcp add context7 npx -y @context7/mcp-server
- Verify:
claude mcp list
Table of contents
Open Table of contents
The Problem: Claude Guessing Outdated APIs
You know the pattern: Claude confidently suggests code that should work, but doesn’t.
Yesterday, I was debugging a Structurizr configuration file (an architecture diagram tool) when I hit this exact problem:
Unexpected tokens at line 457: documentation {
Claude made three confident attempts, restructuring brackets each time. But no amount of bracket juggling would work—Structurizr’s entire documentation {}
syntax had been deprecated for the !docs
directive.
This isn’t a Structurizr problem. It’s the Stripe v2024 problem. The React 19 problem. The Terraform 1.5 problem. Libraries evolve faster than Claude’s training data.
How Context7 Solved It
Context7 is an MCP server that loads current documentation directly into Claude’s context. Not summaries or memories—the actual docs.
Before Context7: Guessing Game
Claude kept trying to restructure my documentation blocks, not knowing the syntax had completely changed:
- Attempt 1: “Move
documentation
block insideworkspace
” - Wrong, it was already inside - Attempt 2: “Add missing closing brace for
views
block” - Still errored - Attempt 3: “Fix the software system reference syntax” - Kept trying variations of the deprecated syntax
After Context7: Instant Fix
With Context7 loaded, Claude saw the real problem immediately:
❌ What I had (deprecated):
documentation {
kinmelApp "README.md"
}
✅ What Structurizr now uses:
!docs docs
Setup (30 Seconds)
# Install
claude mcp add context7 npx -y @context7/mcp-server
# Verify
claude mcp list
# Should see: context7... ✓ Connected
Manual config option: Add to claude_desktop_config.json
at:
- Mac:
~/Library/Application Support/Claude/
- Windows:
%APPDATA%\Claude\
- Linux:
~/.config/Claude/
When to Use Context7
- First wrong suggestion → Load docs immediately
- Version-specific work → “Load Next.js 15 docs via Context7”
- New library integration → Load docs preemptively
- “Method doesn’t exist” errors → Context7 has the real API
Real Impact
My Structurizr session:
- Without Context7: 22 minutes, 3 failed attempts
- With Context7: 2 minutes, 1 correct fix
Pro tip: Combine with CLAUDE.md:
- CLAUDE.md: Your patterns and conventions (see my guide here)
- Context7: External library truth
This pairs perfectly with strategic documentation control—CLAUDE.md keeps AI following your patterns, Context7 ensures it uses correct APIs.
Key Points
- Free, no API keys (by Upstash)
- Secure: Runs locally, only fetches public docs
- Token impact: Adds thousands of tokens per request
- Coverage: Popular libraries work best
- Caveat: Community-maintained, verify critical code