Your first MCP server — claude mcp add
Install your first MCP server in Claude Code or Codex in under two minutes. We pick context7 (library docs) — small, useful, no API key.
Your first MCP server
MCP (Model Context Protocol) is how Claude Code, Codex, and Cursor talk to external tools. An MCP server runs as a subprocess (stdio) or remote HTTP endpoint and exposes a list of "tools" the AI can call. Installing one is two commands.
We start with context7 because it's the lowest-friction win — it gives Claude up-to-date library docs (React, Next.js, Prisma, you name it) without any API keys. Once you've done this once, every other MCP server installs the same way.
Step 1: Pick the client (Claude Code or Codex)
Claude Code uses claude mcp add ... which writes ~/.claude.json.
Codex uses ~/.codex/config.toml directly (or codex mcp add ... if you have CLI 0.x+).
If you have both, do both — they share most servers but the config file differs.
Step 2: Install context7 in Claude Code
claude mcp add context7 -s user -- npx -y @upstash/context7-mcp
Breakdown:
claude mcp add— register a new servercontext7— the local name (whatever you want)-s user— user-scope (vs project-scope.mcp.json)-- npx -y @upstash/context7-mcp— the command that starts the server (npx auto-installs from npm)
npx -y is the magic — first call downloads the package, subsequent calls run from npm cache. No global install pollution.
Step 3: Same in Codex (optional)
Edit ~/.codex/config.toml:
[mcp_servers.context7]
command = "npx"
args = ["-y", "@upstash/context7-mcp"]
Restart Codex (Cmd+Q on macOS, then reopen — VS Code Extension also needs a window reload).
Step 4: Verify
Run aiguide_validate_step. The validator runs claude mcp list and checks that at least one server is registered. To verify context7 specifically:
claude mcp list | grep context7
Or open a fresh Claude Code session and ask "what does the latest Next.js docs say about server actions?" — Claude will call context7's query-docs tool and you'll see the citation.
Step 5: The next servers worth installing
These three are all zero-config (no API keys) and pay off fast. Add them now or save them for later phases:
- sequential-thinking — multi-step reasoning. Tiny, helps on hard problems.
claude mcp add sequential-thinking -s user -- npx -y @modelcontextprotocol/server-sequential-thinking - filesystem — local file operations from a sandboxed root.
claude mcp add filesystem -s user -- npx -y @modelcontextprotocol/server-filesystem /path/you/want/sandboxed - fetch — fetch web pages and parse them as text.
claude mcp add fetch -s user -- npx -y @modelcontextprotocol/server-fetch
After this recipe you have a working MCP setup. The next four recipes layer in memory, web research, code intelligence, and GitHub — the four servers that turn Claude Code from "smart autocomplete" into "second engineer".
claude mcp list 2>&1 | head -20