nextcloud-mcp-connector
by street1983nk
README.md
**English** | [Deutsch](README.de.md) | [Français](README.fr.md)
# MCP Connector for Nextcloud
[](https://github.com/street1983nk/nextcloud-mcp-connector/actions/workflows/ci.yml)
[](https://github.com/street1983nk/nextcloud-mcp-connector/actions/workflows/security.yml)
[](https://scorecard.dev/viewer/?uri=github.com/street1983nk/nextcloud-mcp-connector)
[](https://www.bestpractices.dev/projects/15326)
[](https://apps.nextcloud.com/apps/mcp_connector)
[](LICENSE)
A curated MCP server that connects your Nextcloud (files, calendar, notes, Deck, contacts,
Tables, Talk and Mail) to AI assistants such as Claude, Cursor, ChatGPT or your own agents.
Installed as a Nextcloud ExApp, it is its own OAuth 2.1 authorization server as well.
**Findling + Nextcloud MCP Connector = the retrieval layer for your own RAG.**
[Findling](https://apps.nextcloud.com/apps/findling) makes the content of your documents
searchable, scans included. The connector hands those hits to any MCP client, with exactly
the rights of the asking user; measured in
[tests/integration/test_content_hit_fidelity.py](tests/integration/test_content_hit_fidelity.py).
You bring the model, and no content leaves your server.
## What it does
- 23 tools across nine app families: files, calendar, notes, Deck, contacts, Tables, Talk,
Mail and cloud wide search
- OAuth 2.1 to the MCP authorization specification: dynamic client registration, PKCE S256,
audience bound tokens, refresh rotation with reuse detection and immediate revocation.
Claude.ai and ChatGPT are given one URL and never see a password or an app password
- Every request runs with the rights of the signed in user, so Nextcloud permissions apply
unchanged and the assistant never sees more than you do
- Per user management: every account pauses or resumes its own access and disconnects a single
assistant, on this app's connections page under Settings, Security, MCP Connector
- `prepare_context` bundles a search, the coming week of events, the waiting Talk conversations
and the unread mail counts into one call, each source with its own time budget
- A deliberately small tool set, so this server fits next to your other MCP servers even in
clients with a hard tool limit
- No cron, no indexing, no telemetry, no copy of your data, and no credential is ever logged
## What this server cannot do
- No deleting: no tool issues a DELETE against files, events, notes, cards or contacts
- No overwriting: writes are create-only, and `files_upload` refuses an existing path with a
clear error instead of replacing it
- No user-visible moving or renaming, no share changes and no permission changes; binary
uploads use Nextcloud's private chunk assembly and still refuse an existing destination
- Mail is strictly read only: no sending, no draft, no move, no flag, no delete, and no
attachment download
- No admin access: the server acts as one user and inherits exactly that user's permissions
- No full text search inside file contents unless a search app such as Findling is installed
That is a design constraint and not a promise of good behaviour: a contract test reads the
modules and fails on the first destructive call,
[tests/contract/test_no_destructive_calls.py](tests/contract/test_no_destructive_calls.py).
## Tools
**read** means the tool only reads, **create-only** means it can create new objects but never
modifies or removes existing ones. The table is not maintained by hand: a contract test reads
the live registry and fails if a name or a level disagrees with it.
| Tool | Permission | What it does |
|------|------------|--------------|
| `files_search` | read | Files and folders by name via WebDAV search; contents are not indexed |
| `files_list` | read | The direct children of a folder, with size and modification time |
| `files_read` | read | The content of one file |
| `files_download` | read | Any-size file as bounded embedded-resource chunks |
| `files_read_as_markdown` | read | A DOCX, XLSX, PPTX or PDF file converted to Markdown, in slices |
| `files_upload` | create-only | A new text file or any-size binary upload in base64 chunks; an existing path is refused, never overwritten |
| `calendar_list_events` | read | Events in an explicit time range, with an explicit time zone |
| `calendar_create_event` | create-only | A new event; existing events are never changed |
| `notes_search` | read | Notes by title and content, via the Nextcloud notes search provider |
| `notes_read` | read | One note |
| `notes_create` | create-only | A new note; existing notes are never changed |
| `deck_browse` | read | Deck boards, stacks and cards |
| `deck_create_card` | create-only | A new card in a stack; existing cards are never changed |
| `tables_browse` | read | Tables: the tables, the columns of one, or its rows |
| `tables_create_row` | create-only | A row addressed by column titles; existing rows are never changed |
| `talk_browse` | read | Talk conversations and the history of one; reading leaves no trace |
| `talk_send` | create-only | One message into a conversation; never edited or deleted, switchable off instance wide |
| `mail_browse` | read | Mail accounts, their mailboxes and message envelopes; strictly read only |
| `contacts_search` | read | Address book contacts |
| `unified_search` | read | The Nextcloud unified search across providers, permission aware |
| `prepare_context` | read | Files, notes, cards, the next week of events, waiting Talk conversations and unread mail counts in one call |
| `search` | read | OpenAI compatible search entry point, delegates to unified search |
| `fetch` | read | OpenAI compatible fetch, resolves an id to a file, note, card, event, mail, Talk message or table |
`search` and `fetch` exist because the ChatGPT connector profile requires exactly these two
names and schemas. They are thin wrappers over the tools above, not a second implementation.
An answer of `unified_search`, with both honest cases in it: a hit whose id the read tools
resolve, and a provider whose entries stay a URL instead of an invented id. A provider that
fails or stalls is named under `degraded`, so a partial answer is visibly partial. Notes,
Deck, Tables, Talk and Mail are optional apps; the tool list stays the same everywhere and a
missing app is answered in one sentence, never with an empty result.
```json
{"query":"budget","count":2,"results":[{"id":"file:4711","title":"Budget 2026.md","url":"https://cloud.example.org/index.php/f/4711","provider":"files","kind":"file"},{"id":"url:https://cloud.example.org/index.php/call/abc123","title":"Khaled","url":"https://cloud.example.org/index.php/call/abc123","provider":"talk-conversations","kind":"url","resolvable":false}]}
```
## Switching tool bundles off
- Variable: `NC_MCP_DISABLED_TOOLS`, comma separated bundle names, read at start.
- Where to set it: as a deploy environment variable of the ExApp, either in the deploy
options of the install/update dialog, or on the command line:
`occ app_api:app:register mcp_connector --env "NC_MCP_DISABLED_TOOLS=mail,calendar"`
(unregister first on an existing installation; user connections survive, the container
is recreated). The start log names the bundles that are off.
- Default: unset, every bundle is on.
- Example: `export NC_MCP_DISABLED_TOOLS=mail,calendar`, useful when a second MCP server
already offers mail and calendar and a smaller model confuses the two.
- Bundles and their tools:
- `calendar`: `calendar_list_events`, `calendar_create_event`
- `chatgpt`: `search`, `fetch`
- `contacts`: `contacts_search`
- `context`: `prepare_context`
- `deck`: `deck_browse`, `deck_create_card`
- `files`: `files_search`, `files_list`, `files_read`, `files_download`,
`files_read_as_markdown`, `files_upload`
- `mail`: `mail_browse`
- `notes`: `notes_search`, `notes_read`, `notes_create`
- `search`: `unified_search`
- `tables`: `tables_browse`, `tables_create_row`
- `talk`: `talk_browse`, `talk_send`
- An unknown name, or every name at once, stops the server at start with a message that
lists the valid names.
- Not an access control: `search`, `fetch` and `prepare_context` still reach the content
of a switched off bundle. Use Nextcloud permissions, the `kein-ki` tag or
`NC_MCP_FILES_ROOT` to keep content away from the assistant.
- ChatGPT connectors expect the `chatgpt` bundle (`search`, `fetch`).
- The ExApp declares the variable and logs at start which bundles are switched off.
## Excluding folders: the kein-ki tag
Tag a folder or file with the collaborative tag `kein-ki` and the assistant no longer sees it or anything below it.
Check the setup with `php occ mcp_connector:exclusion:check --admin=<uid>`.
Most important limit: a tag above the root of a share does not protect the shared folder for the recipient, so tag the folder you share.
Setup, all limits and the findings they rest on: [docs/exclusion.md](docs/exclusion.md).
## Architecture
One container, one app: the connector is a Nextcloud ExApp built on FastAPI
and the official MCP SDK, serving Streamable HTTP and stdio from the same
server, and it is its own OAuth 2.1 authorization server bridging into the
Nextcloud login. Every tool call is an HTTP request against Nextcloud's own
APIs (WebDAV, CalDAV, CardDAV, OCS and app REST APIs) made as the signed-in
user, so permissions apply unchanged, and nothing is indexed or copied.
## Security
This server holds **private data**, it takes in **untrusted content** (a mail or a Talk message
is written by somebody else, and for a mail that somebody needs no account on your instance),
and it has an **outgoing channel**, `talk_send`. Those three together are what Simon Willison
calls the [lethal trifecta](https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/), and a
language model does not reliably separate data from instructions. So `talk_send` sits behind
the administration switch `NC_MCP_TALK_SEND`, which closes the outgoing channel for the whole
instance while reading stays untouched, and Mail adds reach with deliberately no way out of its
own. Neither makes prompt injection impossible. The long form, with every countermeasure and
the honest remainder, is in [docs/privacy.md](docs/privacy.md). Every boundary this server
offers on one page, in the order to apply them on confidential data:
[docs/hardening.md](docs/hardening.md). The systematic version, assets, attackers and every
threat with the test that holds its mitigation: [docs/threat-model.md](docs/threat-model.md).
The switches sit under Settings, Administration, Security:
## Installation
Listed in the Nextcloud App Store as
[MCP Connector](https://apps.nextcloud.com/apps/mcp_connector) and installed as an ExApp:
enable AppAPI, register a deploy daemon, then deploy and enable the app. Nextcloud 32 to 35.
On 34.0.3 the apps management interface does this for you, on earlier versions occ is the
reliable path. The walkthrough with the exact commands and the pitfalls that actually happen:
[docs/exapp-install.md](docs/exapp-install.md).
Since 0.2.0 the server also runs without AppAPI. `nc-mcp-oauth` serves the same endpoint,
authorization server and consent screen for a Nextcloud it reaches over HTTPS, and because
no AppAPI header names the account behind a browser there, the consent decision is confirmed
by the OIDC single sign-on Nextcloud already trusts. Setup, secrets and operation:
[docs/standalone-oauth.md](docs/standalone-oauth.md).
[](https://apps.nextcloud.com/apps/mcp_connector)
## Clients
Claude.ai and ChatGPT connect over OAuth with one URL. Claude Desktop, Claude Code, Cursor and
other local clients run the same server over stdio, with a Nextcloud app password:
```bash
uv tool install nextcloud-mcp-connector
export NC_MCP_URL=https://cloud.example.com
export NC_MCP_USER=alice
export NC_MCP_APP_PASSWORD=xxxxx-xxxxx-xxxxx-xxxxx-xxxxx
# Optional: expose only this Nextcloud directory to file tools
export NC_MCP_FILES_ROOT=/Documents/AI
nc-mcp
```
The same server speaks Streamable HTTP for remote clients, on `POST /mcp`, where
`NC_MCP_ALLOWED_HOSTS` is required in practice. Setup step by step, every environment variable
and the three errors that actually happen: [docs/client-setup.md](docs/client-setup.md). OAuth
for administrators: [docs/oauth-setup.md](docs/oauth-setup.md). Automation platforms are
clients too, with one OAuth connection per person: [docs/n8n-setup.md](docs/n8n-setup.md).
When `NC_MCP_FILES_ROOT` is set, `/` becomes that directory for the file tools. For example,
`/scan.pdf` is resolved under `/Documents/AI`, and no file tool can reach its parent folders.
## Privacy
Every call goes to your Nextcloud and returns: nothing runs in the background, no result is
cached, no index is kept. In the HTTP modes the credentials travel per request and are never
stored. Questions users ask: [docs/faq.md](docs/faq.md).
## Enterprise
The audit log is part of this app and not of an add-on. With it on, every tool call is written
down with the account it ran for, the tool, the time, the calling app and the outcome, and
never a parameter value or any part of a result. It is off by default, an administrator
switches it on in the admin settings of this app, and the entries are read with
`occ mcp_connector:audit:read`. Every entry is hash chained to the one before it, and
`occ mcp_connector:audit:verify` walks the chains and names the first place one of them is
broken.
Sign in through the identity provider your organisation already runs arrived with 0.2.0, in
the deployment without AppAPI: the consent decision is confirmed by the OIDC single sign-on
Nextcloud already trusts through `user_oidc`. A service of the organisation can also act in a
user's name with a token it exchanged at that provider, and the setup, the measured limits of
the route and what is still open about it are in
[docs/token-exchange.md](docs/token-exchange.md). Still planned on that road are group
policies.
Request a quote: admin@infranode.dev
## Development
```bash
uv sync
uv run pytest
uv run ruff check .
uv run ruff format --check .
```
`uv run pytest` starts nothing and needs nothing. `uv run pytest -m matrix` starts the HTTP
server as a subprocess, `uv run pytest -m integration` needs the local test Nextcloud from
`compose.test.yml`.
App id, package names and repository name are frozen, see
[docs/app-id-freeze.md](docs/app-id-freeze.md).
## Licence
AGPL-3.0-or-later, see [LICENSE](LICENSE). Donations: [PayPal](https://www.paypal.com/paypalme/KhaledCherifDev)
and [Stripe](https://buy.stripe.com/3cI14n2ke6AbdTPfG22VG00).
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