Using Stack Auth with AI - Stack Auth Documentation

This page is for giving your own coding agent (Claude Code, Cursor, Codex, opencode, …) ongoing knowledge of Stack Auth so it writes Stack Auth code correctly.If you would like to use Stack Auth to power your own CLI, see the CLI Authentication page.

There are three ways to give a coding agent working knowledge of Stack Auth. They differ only in how the instructions reach the agent — the knowledge is the same.

Web Fetch

Paste a one-line prompt — your agent fetches the live skill on demand.

Skill

Install the Stack Auth SKILL.md file so your agent loads it automatically.

MCP

Connect your agent to the Stack Auth MCP server for live docs and ask_stack_auth search.

Option 1: Web fetch (recommended)

Most coding agents now support web fetch out of the box, so you can simply tell your agent to use Hexclave’s skill from the internet. To do so, paste the prompt below into your coding agent:

One-shot prompt

Fetch https://skill.stack-auth.com and follow it for this task.

The fetched SKILL.md indexes the entire Stack Auth docs sidebar and tells the agent to pull fresh content for whichever surface you’re touching (auth, orgs/teams, payments, emails, analytics, the CLI). It is purely a reference — paste it whenever you want the agent to use Stack Auth knowledge.

Option 2: Skill

Install the skill once so your agent loads it automatically every time Stack Auth is relevant — no copy-paste required.

Cli install
Copy-paste prompt

The fastest way to install the Stack Auth skill for a Claude Code-style agent or similar:

Terminal

npx -y skills add stack-auth/stack-auth --skill stack-auth

This detects your agent and installs the skill in the correct location (per-project or global) automatically. From then on, your agent picks it up whenever the conversation touches Stack Auth.

If your agent can’t run the npx command above, paste the prompt below into the chat. The agent will fetch SKILL.md and drop it into the right location for your agent — per-project if a project-scoped agent folder exists, global otherwise.

Skill install prompt

Install the Stack Auth skill (`SKILL.md`) for me so you load it automatically on future Stack Auth tasks. The canonical file lives at:

https://raw.githubusercontent.com/stack-auth/stack-auth/dev/skills/stack-auth/SKILL.md

These are the same install locations the `skills` CLI (https://github.com/vercel-labs/skills) uses — match them exactly so the file is picked up the same way.

Do this in one shot using smart defaults; only stop to ask a single multiple-choice question at the end if I want to change anything.

1. **Detect the agent.** Identify which coding agent is running you (Claude Code, Codex, Cursor, opencode, Windsurf, Roo, Kilo, Amp, Antigravity, Cline, Continue, Crush, Augment, etc.). If you genuinely can't tell, default to Claude Code.

2. **Pick the default scope.** Look for an existing agent folder in the current project root: `.claude/`, `.agents/`, `.cursor/`, `.codex/`, `.opencode/`, `.windsurf/`, `.roo/`, `.kilocode/`, `.augment/`, `.continue/`, `.crush/`, etc.
   - If any such folder exists → default to **project** scope.
   - Otherwise → default to **global** scope.

3. **Resolve the install directory.** Write `SKILL.md` to `<skills-dir>/stack-auth/SKILL.md`, where `<skills-dir>` comes from this table (mirrors `vercel-labs/skills/src/agents.ts`):

   | Agent | Project `<skills-dir>` | Global `<skills-dir>` |
   | --- | --- | --- |
   | Claude Code | `.claude/skills` | `~/.claude/skills` (or `$CLAUDE_CONFIG_DIR/skills`) |
   | Codex | `.agents/skills` | `~/.codex/skills` (or `$CODEX_HOME/skills`) |
   | Cursor | `.agents/skills` | `~/.cursor/skills` |
   | opencode | `.agents/skills` | `~/.config/opencode/skills` (XDG) |
   | Windsurf | `.windsurf/skills` | `~/.codeium/windsurf/skills` |
   | Amp | `.agents/skills` | `~/.config/agents/skills` (XDG) |
   | Antigravity | `.agents/skills` | `~/.gemini/antigravity/skills` |
   | Cline | `.agents/skills` | `~/.agents/skills` |
   | Roo Code | `.roo/skills` | `~/.roo/skills` |
   | Kilo Code | `.kilocode/skills` | `~/.kilocode/skills` |
   | Augment | `.augment/skills` | `~/.augment/skills` |
   | Continue | `.continue/skills` | `~/.continue/skills` |
   | Crush | `.crush/skills` | `~/.config/crush/skills` |

   For any agent not listed, follow its documented skills directory or fall back to `.agents/skills` (project) / `~/.<agent>/skills` (global).

4. **Install.** Download `SKILL.md` once to a stable cache location — `~/.cache/stack-auth/SKILL.md` (or `$XDG_CACHE_HOME/stack-auth/SKILL.md`) — then create a **symlink** at `<skills-dir>/stack-auth/SKILL.md` pointing to that cached file. Create missing parent directories. If the target path already exists, replace it (overwrite the symlink, or back up and replace a regular file). Symlinking means future re-installs at additional scopes/agents reuse the same source file, and re-running the prompt after an update to the cached file picks up automatically. If the platform doesn't support symlinks (e.g. Windows without dev mode), fall back to copying the file verbatim.

5. **Confirm and offer alternatives.** Print the absolute symlink path and the cache target it points to. Then ask me a single multiple-choice question covering anything I might want to change, e.g.:

   ```
   Installed Stack Auth skill at <path> → <cache path>. Want to change anything?
   a) Keep it — done
   b) Also symlink at the opposite scope (<other path>)
   c) Install for a different agent instead
   d) Symlink into additional agents too
   ```

   Only act on whichever letter I pick. Don't pre-ask before the first install. Additional installs just create more symlinks pointing at the same cached `SKILL.md`.

Installing the file is the only goal of this prompt — do not act on the skill's contents yet.

Option 3: MCP

The Stack Auth MCP server (https://mcp.stack-auth.com/mcp) gives your agent live access to Stack Auth docs and skill via prompts, resources and an ask_stack_auth tool that searches the docs with citations. Install it once per agent — it stays available across every project.

One-click install
Config files
Ask your agent

Add to Cursor

Opens Cursor and adds stack-auth to your MCP config.

Add to VS Code

Opens VS Code and adds stack-auth to your MCP config.

For the up-to-date list of one-click install buttons for every client (Cursor, VS Code, Claude Desktop, Windsurf, ChatGPT, Gemini, …), visit mcp.stack-auth.com in your browser.

Add to ~/.cursor/mcp.json (global) or .cursor/mcp.json (project):

mcp.json

{
  "mcpServers": {
    "stack-auth": {
      "url": "https://mcp.stack-auth.com/mcp"
    }
  }
}

Terminal

claude mcp add --transport http stack-auth https://mcp.stack-auth.com/mcp

Terminal

code --add-mcp '{"type":"http","name":"stack-auth","url":"https://mcp.stack-auth.com/mcp"}'

Terminal

codex mcp add stack-auth --url https://mcp.stack-auth.com/mcp

Or add to ~/.codex/config.toml:

config.toml

[mcp_servers.stack-auth]
url = "https://mcp.stack-auth.com/mcp"

mcp.json

{
  "mcpServers": {
    "stack-auth": {
      "serverUrl": "https://mcp.stack-auth.com/mcp"
    }
  }
}

Add to ~/.gemini/settings.json:

settings.json

{
  "mcpServers": {
    "stack-auth": {
      "httpUrl": "https://mcp.stack-auth.com/mcp",
      "headers": {
        "Accept": "application/json, text/event-stream"
      }
    }
  }
}

For Claude Desktop, ChatGPT, and copy-paste markdown blocks you can drop into your project README, visit mcp.stack-auth.com.

If your agent can edit its own config, paste this prompt:

MCP install prompt

Install the Stack Auth MCP server for me. The server URL is https://mcp.stack-auth.com/mcp (HTTP transport).

Detect which coding agent I'm using and add the server to the correct config file:
- Claude Code → run `claude mcp add --transport http stack-auth https://mcp.stack-auth.com/mcp`
- Cursor → `~/.cursor/mcp.json`
- VS Code → run `code --add-mcp '{"type":"http","name":"stack-auth","url":"https://mcp.stack-auth.com/mcp"}'`
- Codex → `~/.codex/config.toml`
- opencode → `~/.config/opencode/opencode.json`
- Gemini CLI → `~/.gemini/settings.json`

If this repo already has a project-scoped MCP config (`.cursor/mcp.json`, `.vscode/mcp.json`, `.claude.json`, `.codex/config.toml`, etc.), install it there instead of the global location.

After installing, confirm by listing the registered MCP servers.

Project vs. global scope

The install prompts above follow the same rule for picking project-vs-global scope:

Detected in project root	Skill / MCP install scope
`.claude/`, `.cursor/`, `.vscode/mcp.json`, `.codex/`, `.opencode/`	Project (inside the existing folder)
None of the above	Global (user-level config for the detected agent)

This keeps shared repos clean (project-scoped config lives next to the code) and keeps your personal projects ergonomic (one global install, available everywhere).

Documentation Index

Web Fetch

Skill

MCP

​Option 1: Web fetch (recommended)

​Option 2: Skill

​Option 3: MCP

Add to Cursor

Add to VS Code

​Project vs. global scope

Option 1: Web fetch (recommended)

Option 2: Skill

Option 3: MCP

Project vs. global scope