zotmcp

An MCP server embedded in Zotero 10. Search, read, annotate and manage My Library from any MCP client.

Requirements

• Zotero 10 (strict_min_version 10.0)

• Zotero's HTTP server enabled — Settings → Advanced → Allow other applications on this computer to communicate with Zotero. The plugin says so loudly at startup if it is off, and does not open a socket of its own.

Related MCP server: zotero-mcp

Connecting

The endpoint lives on Zotero's own HTTP server:

POST http://127.0.0.1:23119/zotmcp/mcp
Content-Type: application/json

It speaks MCP over JSON-RPC 2.0 and is stateless — no session id, and tools/call works without a prior initialize.

If the port differs, Settings → Zotmcp shows the exact URL.

Zotero 10 drops requests that look like they come from a web page: a User-Agent beginning Mozilla/, or any Origin header. A client in that position must send Zotero-Allowed-Request: 1, or it will see the connection close with no response. Ordinary non-browser clients need nothing extra.

Security

Writes are not gated. Any local program that can reach Zotero's HTTP server can read and change this library through this endpoint, including running arbitrary privileged scripts through zotero_script. There is no confirmation step. The mitigations are that the server is loopback-only and that Zotero 10 blocks browser-originated requests.

Edits, trashing, merges and collection deletion all land on Zotero's own undo stack, so Ctrl+Z reverses them — Zotero 10 trashes rather than erases, and trashed objects can also be restored. What is not undoable is creating an object and permanently deleting one from the trash. The tools say which applies in their results.

A zotero_script write is not undoable by default, because a script's own saveTx() calls carry no undo label. Pass transaction: true to run the script inside one transaction, which makes every change it saves a single undo step; the tradeoff is that the database is held for the script's whole run.

Tools

Fourteen modal tools, kept small so the whole surface is cheap to send on every request. tools/list is generated from the registry, so this list cannot drift from the code without failing a test.

Plus three MCP resources: zotero://collections, zotero://items/{itemKey}, zotero://collections/{collectionKey}/items.

Firefox clipper

firefox-clipper/ is a companion Firefox extension that saves the current tab into Zotero as a clean webpage snapshot. It POSTs a single library_import call (kind: "url") to this endpoint; Zotero then loads the page in a hidden browser, extracts the readable article with Defuddle, and stores a self-contained HTML snapshot with images embedded for offline reading.

The release workflow signs it through Mozilla's AMO API and attaches zotmcp-clipper-<version>.xpi to the GitHub release for permanent install; it can also be loaded temporarily via about:debugging. See firefox-clipper/README.md for install and usage.

Scope

My Library only — group libraries are refused rather than silently mixed in. No semantic search and no external scholarly lookup.

Reading is built on Zotero 10's structured document text, so PDF and EPUB share one path and sections come from the document's own outline. A text-located highlight is placed character-exact where the quote's geometry can be resolved (a CFI range in an EPUB, page rectangles in a PDF) and reports granularity: "exact", falling back to the whole containing paragraph with granularity: "block" when it cannot.

Icon

addon/content/icons/icon.svg is the source; the PNGs beside it are rendered from it:

for s in 32 48 96; do
  inkscape --export-type=png --export-filename=addon/content/icons/icon-$s.png \
    --export-width=$s --export-height=$s addon/content/icons/icon.svg
done

Design

docs/design.md covers the architecture, the decisions and their reasons, the Zotero 10 platform behaviour the implementation depends on, and the known limitations.

Releasing

npm run release behaves differently by environment. Run locally it bumps the version, commits, tags and pushes; the tag then triggers the release workflow, which runs the same command in CI where it instead publishes a release tagged v<version> with the XPI, plus a release tagged release carrying update.json — the URL the plugin's auto-update checks.

npm run release patch    # or minor, major, or an explicit version

Development

npm install
npm run build        # bundle + typecheck, produces .scaffold/build/zotmcp.xpi
npm test             # typecheck + unit tests
npm run lint:fix

Unit tests run in plain Node against a fake gateway, so they need no Zotero.

Integration tests run inside a real Zotero:

cp .env.example .env   # point ZOTERO_PLUGIN_ZOTERO_BIN_PATH at a Zotero binary
npm run test:integration

A Flatpak install exposes no binary, so point that variable at a wrapper script that execs flatpak run org.zotero.Zotero "$@". Use a scratch profile: the tests create and erase fixture items, and a second Zotero cannot share the running instance's profile or its port.