MCP — Model Context Protocol
USB-C For AI — One Protocol, Every Tool
Any compliant host plugs into any compliant server. 10,000+ in production by Dec 2025; a typical 5-server setup adds ~58 tools and ~55K tokens of context. 3–6 servers in active use is right — more bloats the tool list and hurts decision quality.
claude
> claude mcp list
github · postgres · play…
8 servers · 58 tools
>
GitHub
Issues, PRs, repo search.
Postgres MCP Pro
Read/write + EXPLAIN + index tuning.
Playwright
Drive a real browser via a11y.
Notion
Live docs & specs as RAG.
Linear
Issues, sprints, cycle state.
Sentry
Prod errors w/ stack traces.
Stripe
Read-only billing & subs.
Filesystem
Sandboxed reach beyond root.
.claude/settings.json
Three Buckets — Deny Beats Allow
First match wins. Read(.env) in deny is the single highest-ROI line on the page.
Deny → Ask → Allow
Allow
Silent · safeBash(npm run *)Dev Loop
Bash(git diff *)Read State
Bash(git commit *)Feature Branch
WebFetch(docs.claude.com)Trusted Domain
Ask
Prompts · mutatesEditTouches Files
WriteCreates Files
Bash(supabase *)Migrations
Bash(npm run deploy *)Ships Code
Deny
Refused outrightRead(.env)Highest ROI
Bash(rm -rf *)Destructive
Bash(* DROP TABLE *)Data Loss
Bash(git push * --force *)Rewrites Main