vault-mcp

Authenticated remote MCP server on Cloudflare Workers that exposes a private, GitHub-hosted Obsidian vault to both claude.ai (Web / Desktop / iPhone) and Claude Code — one free deployment serving every Claude surface. It reads notes, creates/overwrites them, and deletes them; it never renames or moves. Every mutation is a git commit, so deletes stay revertable.

It works against the vault through the GitHub API, so the source repo can stay private and there is no always-on machine to maintain. Deploy your own instance with C3 (one command) or clone it manually — both are covered below. Your vault target is set via secrets, so the committed config ships generic.

What it does

• Auth: GitHub OAuth via @cloudflare/workers-oauth-provider. Users sign in with GitHub; only logins in VAULT_ALLOWED_GITHUB_LOGINS get any tools at all.

• Accesses the vault through the GitHub API using a separate fine-grained PAT (VAULT_GITHUB_TOKEN) scoped to Contents Read + Write on the one vault repo.

• Transport: Streamable HTTP at /mcp.

Tools

Related MCP server: obsidian-mcp

Two GitHub tokens, two jobs

Keeping them separate means logging in never grants repo write via the OAuth app, and the vault PAT is scoped to exactly one repo. Keep the PAT scoped to that single repo — this server needs read and write on the vault, but nothing beyond it.

Access scope

Path visibility is controlled by two settings that default in src/config.ts; override either per deploy with a secret of the same name (wrangler secret put):

• VAULT_ALLOWED_PREFIXES — if non-empty, only paths under these prefixes are exposed (default: empty = whole repo).

• VAULT_DENIED_PREFIXES — always hidden (default: .git/,.obsidian/,.claude/).

read_note, write_note, and delete_note all reject absolute paths and .. traversal, and write_note/delete_note only accept markdown paths — the deny/allow policy applies equally to reads, writes, and deletes, so a mutation can never escape into .git/, .obsidian/, or agent dirs. To hide (and block writes/deletes to) additional folders, override VAULT_DENIED_PREFIXES with your extra prefixes.

Quick start (C3)

Scaffold your own copy with Cloudflare's C3:

npm create cloudflare@latest vault-mcp -- --template wakita181009/vault-mcp
cd vault-mcp

That clones the project and installs dependencies — but not the one-time setup: you still create the KV namespace, GitHub OAuth app, and fine-grained PAT (Contents: Read and write), and set the secrets. Continue with Setup from step 2 (step 1 is done for you). Cloning the repo directly works too; then start from step 0.

Setup

0. Prereqs

pnpm install
pnpm exec wrangler login    # Cloudflare auth

1. Point it at your vault

Your vault target (VAULT_OWNER / VAULT_REPO) and login allowlist (VAULT_ALLOWED_GITHUB_LOGINS) are secrets, set in step 5 — you don't edit wrangler.jsonc to point it at your repo. The committed wrangler.jsonc ships generic; its only per-deploy value is the KV namespace id (step 2). Everything else defaults in src/config.ts and is optional — override any of these per deploy with wrangler secret put <NAME>:

• VAULT_BRANCH — branch of the vault repo to read (default main).

• VAULT_ALLOWED_PREFIXES / VAULT_DENIED_PREFIXES — see Access scope above.

2. Create the KV namespace (stores OAuth grants)

pnpm exec wrangler kv namespace create OAUTH_KV

Put the returned id into wrangler.jsonc under kv_namespaces[0].id.

3. Create the PAT for accessing the vault

GitHub → Settings → Developer settings → Fine-grained tokens → Generate:

• Resource owner: your account, Repository access: Only your vault repo

• Permissions: Contents → Read and write

Save the token for VAULT_GITHUB_TOKEN below.

4. Create the GitHub OAuth App (login)

You need two apps (or reuse one with a second callback): local + production.

GitHub → Settings → Developer settings → OAuth Apps → New:

• Local: Homepage http://localhost:8788, Callback http://localhost:8788/callback

• Prod: Homepage https://vault-mcp.<subdomain>.workers.dev, Callback https://vault-mcp.<subdomain>.workers.dev/callback

Note each app's Client ID and generate a Client Secret.

5a. Run locally

cp .dev.vars.example .dev.vars    # LOCAL OAuth app, PAT, vault owner/repo/logins
openssl rand -hex 32              # value for COOKIE_ENCRYPTION_KEY
pnpm dev                          # http://localhost:8788/mcp

Test with the MCP inspector:

pnpm dlx @modelcontextprotocol/inspector@latest
# connect to http://localhost:8788/mcp, complete the GitHub login

5b. Deploy to production

pnpm exec wrangler secret put GITHUB_CLIENT_ID            # PROD OAuth app
pnpm exec wrangler secret put GITHUB_CLIENT_SECRET
pnpm exec wrangler secret put COOKIE_ENCRYPTION_KEY       # openssl rand -hex 32
pnpm exec wrangler secret put VAULT_GITHUB_TOKEN          # fine-grained PAT, Contents R/W on the vault repo
pnpm exec wrangler secret put VAULT_OWNER                 # GitHub owner of the vault repo
pnpm exec wrangler secret put VAULT_REPO                  # vault repo name
pnpm exec wrangler secret put VAULT_ALLOWED_GITHUB_LOGINS # comma-separated allowed logins
pnpm run deploy

Endpoint: https://vault-mcp.<subdomain>.workers.dev/mcp

6. Connect the clients

• claude.ai (Web): Settings → Connectors → add custom connector with the /mcp URL. Registration is Web-only; it then syncs to Desktop and the iPhone app.

• Claude Code: claude mcp add --transport http vault https://vault-mcp.<subdomain>.workers.dev/mcp (completes the OAuth flow in the browser). Works even on a Mac that has not cloned the vault.

Development

pnpm typecheck     # verify generated Worker types, then run tsc --noEmit
pnpm lint          # biome lint ./src
pnpm test          # vitest run
pnpm cf-typegen    # regenerate worker-configuration.d.ts after editing wrangler.jsonc
pnpm dev           # local Worker at :8788

Secrets are typed in src/env.d.ts (they are not part of the wrangler types output). After changing wrangler.jsonc bindings/vars, rerun pnpm cf-typegen.

Layout

src/
├── index.ts                   # OAuthProvider + VaultMCP (McpAgent) wiring; registers the tools
├── tools.ts                   # MCP tool handlers (list/read/write/delete/search) + result & allowlist helpers
├── guard.ts                   # login-allowlist gate wrapping the MCP API handler
├── vault.ts                   # GitHub API access layer: list/read/write/delete/search + path-visibility policy
├── config.ts                  # env schema + defaults; parseEnv validates at startup
├── env.d.ts                   # secret bindings type augmentation
└── auth/
    ├── github-handler.ts      # GitHub OAuth login flow (Hono)
    ├── approval-dialog.ts     # OAuth approval dialog + HTML sanitization
    ├── workers-oauth-utils.ts # OAuth state / CSRF / approved-clients cookie
    └── utils.ts               # upstream OAuth authorize URL + token exchange

Tests live in tests/ (Vitest), mirroring the src/ layout.

Derived from Cloudflare's remote-mcp-github-oauth template.