claude-ms-todo/mcp-extension

Microsoft To Do — Claude Desktop extension (.mcpb)

A one-click Claude Desktop extension that connects Claude to Microsoft To Do. It wraps the same core Graph client as the ms-todo skill (MSTodoClient) and exposes it as MCP tools over stdio. Each user signs in as themselves (delegated, browser auth-code + PKCE); their refresh token is cached privately on their own machine.

The built artifact is ms-todo.mcpb.

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For end users — install in Claude Desktop

1. Get ms-todo.mcpb from your admin.
2. Open Claude Desktop → Settings → Extensions.
3. Drag ms-todo.mcpb in (or click Install extension and select it).
4. Optionally set your Time zone in the extension's settings (used for due / start / reminder dates; default UTC). Leave Read-only mode off for full access.
5. In a chat, say: "Sign in to Microsoft To Do." Claude runs the todo_login tool, your browser opens to the Microsoft sign-in page, you approve, and you're connected. (You only do this once.)
6. Try it: "What's on my To Do list?", "Add 'call dentist' due Friday to Tasks."

If Claude Desktop warns that the extension is not verified/signed, that's expected for an internally distributed extension — install it anyway (or have your admin sign it, see below).

What it can do (tools)

todo_login, todo_logout, todo_test, todo_list_lists, todo_list_tasks, todo_get_task, todo_create_task, todo_update_task, todo_complete_task, todo_delete_task, todo_create_list, todo_update_list, todo_delete_list, todo_list_checklist, todo_add_checklist_item, todo_check_checklist_item, todo_delete_checklist_item.

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For the admin — one-time Entra setup (org-wide)

The extension ships with a baked-in public-client app id and tenant id (in manifest.json → server.mcp_config.env). There is no client secret — these identifiers are not secrets. For smooth org-wide use, in entra.microsoft.com on that app registration:

1. Authentication → Mobile and desktop applications — ensure redirect URIs http://localhost and http://127.0.0.1 are present (the extension uses a loopback redirect during sign-in). Already configured for the current app.
2. API permissions — delegated Tasks.ReadWrite, offline_access, User.Read. Click Grant admin consent for <tenant> so individual users are not prompted to consent (and so it works even if user consent is disabled in your tenant).
3. The tenant id is baked single-tenant, so only your org's accounts can sign in. To support guests/other tenants, change the app to multi-tenant and set TODO_TENANT_ID to organizations (then rebuild).

To change the baked id/tenant, edit manifest.json and rebuild (below).

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Rebuilding the .mcpb

Requires Node 18+. From this directory:

npm run pack

That runs three steps: sync (copy the canonical graph.mjs from the skill into server/lib/), npm ci --omit=dev (install runtime deps to bundle), and mcpb pack (zip into ms-todo.mcpb). Or run them manually:

node scripts/sync-core.mjs
npm ci --omit=dev
npx -y @anthropic-ai/mcpb pack . ms-todo.mcpb

Useful checks:

npx -y @anthropic-ai/mcpb validate manifest.json
npx -y @anthropic-ai/mcpb info ms-todo.mcpb

Signing — currently disabled

Unsigned extensions install with a "not verified" warning, which is fine for internal distribution (just click through it).

⚠️ Do not sign with mcpb sign right now. As of @anthropic-ai/mcpb 2.1.2 (and 2.0.x/2.1.x), sign corrupts the bundle: it writes an invalid ZIP EOCD comment length, so Claude Desktop fails to open it ("Invalid comment length … extra bytes at the end of the file") and mcpb verify reports it as unsigned. Ship the unsigned bundle until this is fixed upstream.

When signing works again (or with a CA-trusted cert deployed to your fleet), the command is:

npx -y @anthropic-ai/mcpb sign ms-todo.mcpb --cert cert.pem --key key.pem

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How it differs from the Claude Code skill

	ms-todo skill	this .mcpb extension
Host	Claude Code (CLI/IDE) on your machine	Claude Desktop
Surface	node todo.mjs … commands	MCP tools (todo_*)
Sign-in	node todo.mjs login	todo_login tool ("sign in to Microsoft To Do")
Core client	scripts/lib/graph.mjs	the same file, synced into server/lib/

The Graph + auth logic lives in one place; this bundle is just a thin MCP wrapper plus a manifest. Token cache defaults to ~/.ms-todo/token-cache.json per user.