gws-mcp

A small, self-contained MCP server for Google Tasks, Calendar, and Drive — read-write, with one hard rule: every write requires explicit human approval before it executes.

Status: alpha (v0.1.0). The full designed surface — 25 tools across Tasks, Calendar, and Drive — is implemented and tested (46 tests, both approval modes). Not yet battle-hardened against real-world API quirks.

Why another Google MCP?

There is no official Google MCP server for consumer Workspace data, and the community options are broad (10+ services) and mostly unmaintained. This one is deliberately narrow:

• Three services only — Tasks, Calendar, Drive. Smaller code, smaller audit surface.

• Local stdio server — spawned by your MCP client (Claude Code, Gemini CLI, …). Nothing hosted, nothing listening on a network. The server only ever sees tool calls, never your prompts.

• BYO OAuth — you create your own Google Cloud OAuth client and grant scopes to yourself. No shared credentials anywhere.

• Tokens in the OS keyring (Secret Service / KDE Wallet / macOS Keychain) — never plaintext on disk.

Related MCP server: google-workspace-mcp-server

The write-approval invariant

Read tools (list_*, get_*, search_*, read_*) run freely. Mutating tools (create_*, update_*, complete_*, move_*, trash_*, delete_*) cannot execute without a human saying yes, enforced in layers:

1. MCP elicitation (primary): before executing, the server sends a human-readable preview through the client UI — the confirmation goes directly to the human, so the model cannot approve its own writes.

2. Two-step fallback (clients without elicitation): the first call returns a preview + one-time confirm token and mutates nothing; only a second call with the token executes. All executed writes are logged to stderr.

3. Tool annotations (readOnlyHint / destructiveHint) + the strict naming convention, so client permission systems can auto-allow reads and always-prompt writes.

Destructive operations are softened where the API allows it: Drive "delete" is trash, never a hard delete.

Planned tool surface (~22 tools)

OAuth scopes: tasks, calendar.events (events only — no ACL/settings access), drive.

Stack

Python 3.12+ · uv · official mcp SDK (FastMCP, stdio) · google-api-python-client + google-auth-oauthlib · keyring · pytest + ruff.

Quick start

1. Bring your own OAuth client (one-time, ~30 min): in the Google Cloud console create a project, enable the Tasks, Calendar, and Drive APIs, create an OAuth 2.0 Desktop app client, and download its JSON to ~/.config/gws-mcp/credentials.json (chmod 600). No credentials ever ship with, or are stored by, this project — the OAuth grant lives in your OS keyring.

2. Authenticate (interactive, opens a browser):

   git clone https://github.com/purplespacecat/gws-mcp && cd gws-mcp
   uv sync
   uv run gws-mcp auth          # then: uv run gws-mcp auth --status

3. Wire it into your MCP client (stdio):

   # Claude Code
   claude mcp add google-workspace -- uv --directory /path/to/gws-mcp run gws-mcp
   # Gemini CLI
   gemini mcp add google-workspace uv -- --directory /path/to/gws-mcp run gws-mcp

   In clients that support MCP elicitation, write approvals appear as UI prompts; in clients that don't, writes return a preview + one-time confirm token and nothing mutates until confirm_write is called.

Contributing

Issues and PRs are welcome — see CONTRIBUTING.md. All contributions are reviewed before merge; PRs that touch auth, scopes, or the write-approval layer get extra scrutiny.

License

MIT