istefox-dt-mcp

MCP server for DEVONthink 4 — outcome-oriented tools, optional local RAG, privacy-first. Stack: Python 3.12 + FastMCP + ChromaDB + uv.

0.3.0 — current release (May 2026). Seven MCP tools end-to-end, preview-then-apply with audit log + 3-state selective undo on both file_document and bulk_apply, .mcpb bundle installable in Claude Desktop. Vector RAG is opt-in experimental — see ADR-008. For day-to-day status, see handoff.md; for project constraints, see CLAUDE.md; for design decisions, see docs/adr/.

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Quick Install (3 ways)

Path	Best for	Prerequisites
A — .mcpb desktop extension (recommended)	Claude Desktop users, zero-config	Claude Desktop ≥ 0.8
B — pipx install (standalone CLI)	CLI users, other MCP hosts	Python 3.12, pipx
C — Source / dev install	Contributors, debugging	uv, git

A — .mcpb desktop extension (recommended)

Drag-and-drop into Claude Desktop, one-click. The bundle handles its own runtime and dependencies.

1. Download the latest .mcpb from GitHub Releases.
2. Drag it onto the Claude Desktop window (or Settings → Developer → Install Bundle).
3. On first use, macOS will ask for AppleEvents permission — click Allow.

B — pipx install (standalone CLI)

pipx install git+https://github.com/istefox/istefox-dt-mcp

Then add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "istefox-dt-mcp": {
      "command": "istefox-dt-mcp",
      "args": ["serve"]
    }
  }
}

C — Source / dev install

git clone https://github.com/istefox/istefox-dt-mcp.git
cd istefox-dt-mcp
uv sync --all-packages
uv run istefox-dt-mcp doctor

See Setup for full details (macOS permissions, install troubleshooting).

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Prerequisites

• macOS 14+ (Sonoma or later)
• DEVONthink 4 (Pro or standard, any license) installed and running
• Disk space: ~300 MB for the bundle, +2 GB if you enable RAG with bge-m3
• AppleEvents permission for the terminal (pipx/dev) or for Claude Desktop (.mcpb) — requested automatically on first use

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What you can ask Claude

Examples of natural prompts and the MCP tool each one triggers. All examples assume Claude Desktop with the connector installed and DEVONthink running.

• "Find everything about 'antivibration mounts' from the last 2 years" → search (BM25 by default; hybrid if RAG is enabled)
• "What did we propose to Customer X?" → ask_database (BM25 + synthesis; vector if RAG opt-in is on — see RAG)
• "Find documents similar to this PDF" (with a record selected in DT) → find_related (DT's native See Also/Compare)
• "File this attachment in /Inbox/Triage and tag it urgent" → file_document with preview, shows what it will do, then commit with confirm_token
• "Move every March PDF from the Inbox to /Archive/2026" → bulk_apply (batch dry-run + per-record selective apply)
• "Which databases are open in DT?" → list_databases (read-only, 5-min cache)
• "Dammi una panoramica di tutte le bollette del 2025 raggruppate per mese e tag" → summarize_topic (retrieval + server-side clustering by date and tags)

Write tools (file_document, bulk_apply) are dry-run by default: the first call always returns a preview. Apply requires an explicit confirm_token. The returned audit_id enables selective undo via the CLI.

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Privacy & security

The connector is designed privacy-first and local-only:

• Everything stays on your machine: no data leaves it. No telemetry, no cloud embeddings, no analytics. The embedding model (if you enable RAG) runs locally via sentence-transformers.
• Append-only SQLite audit log for every operation (reads included) at ~/.local/share/istefox-dt-mcp/audit.sqlite. Default 90-day retention, configurable.
• Write tools always default to dry_run=true, with a preview-then-apply pattern guarded by a short-TTL confirm_token (5 min default).
• Selective undo via audit_id: every write op stores the before-state and is restorable with istefox-dt-mcp undo <audit_id>.
• Clean-room implementation, MIT license: no code copied from GPL-licensed projects (see Legal constraints).
• Suitable for sensitive data: contracts, invoices, personal notes, customer correspondence.

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Roadmap

Version	What	References
0.1.0 (May 2026)	6 MCP tools, audit + undo, .mcpb bundle, BM25-only retrieval by default	—
0.2.0 (May 2026)	7th tool summarize_topic, 3-state drift detection on file_document undo, real-data VCR cassettes from a fixture DT4 DB	ADR-005
0.3.0 (May 2026)	Per-op 3-state drift detection on bulk_apply undo, one-shot release pipeline (auto-trigger MCP Registry publish)	—
0.4.0+ (Q4 2026)	HTTP transport + OAuth multi-device, create_smart_rule, RAG benchmark cross-corpus + flip default embedding model	ADR-004, ADR-008

Full backlog in handoff.md.

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Troubleshooting top 5

Error	Symptom	Fix
DT_NOT_RUNNING	All tools fail at startup	DEVONthink isn't running — launch it (Spotlight: DEVONthink)
PERMISSION_DENIED (-1743)	First Apple Event errors out	System Settings → Privacy & Security → Automation → enable the toggle for DEVONthink under your terminal or Claude Desktop
DATABASE_NOT_FOUND	file_document or bulk_apply rejects the path	destination_hint is missing the database prefix — use /Inbox/<group> (with leading slash), not /<group>
uv binary not found	The .mcpb bundle won't start on first run	brew install uv (or curl -LsSf https://astral.sh/uv/install.sh | sh), then disable + re-enable the extension in Claude Desktop
drift_state: hostile_drift (on undo)	Undo refuses to roll back	The record was modified after the original apply by something other than your prior undo. Run istefox-dt-mcp audit list --recent for context, inspect drift_details in the response, then add --force if the rollback is still what you want. Note: if drift_state: already_reverted, the record is already back to the pre-apply state — no --force needed, undo returns a no-op

For anything not listed: uv run istefox-dt-mcp doctor produces a full diagnostic report (DT running, permissions, cache, RAG state).

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Status

0.3.0 current release (May 2026): 7 MCP tools end-to-end, 3-state drift detection on both file_document and bulk_apply undo paths, .mcpb bundle distributable, MCP Registry entry auto-published on tag push. 222 unit + contract tests green, mypy clean across 37 source files. CI on Ubuntu (lint + mypy + unit + contract) and macOS-14 (import + bundle smoke + nightly).

Previous milestones: 0.2.0 (May 2026) — summarize_topic tool + 3-state drift on file_document + real-data VCR cassettes via record-cassette CLI. 0.1.0 (May 2026) — first public release, 6 tools, BM25-only retrieval.

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What it does

A DEVONthink 4 connector for MCP that goes beyond a 1:1 wrapper of the scripting dictionary.

The seven tools:

Tool	Type	Notes
list_databases	read	Open databases, with 5-min cache
search	read	BM25 (default) + optional vector hybrid (RRF) when RAG is enabled
find_related	read	Wraps DT's native See Also / Compare
ask_database	read	BM25 + synthesis (default) + optional vector retrieval
summarize_topic	read	Retrieval + server-side clustering by date/tags/kind/location (0.2.0)
file_document	write	dry_run by default + preview-then-apply + selective undo
bulk_apply	write	Batch ops with dry_run + per-op outcomes

The two write tools follow the preview-then-apply pattern: calling them with dry_run=true returns a preview plus a preview_token (the audit_id of the dry-run); a second call with dry_run=false plus confirm_token=<preview_token> actually applies the change. The returned audit_id enables selective undo via the CLI.

Still on the post-MVP list: create_smart_rule — see ADR-004.

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Stack

Component	Tech	Reference
Language	Python 3.12	ADR-001
MCP framework	FastMCP 3.x	ADR-001
Validation	Pydantic v2	ADR-001
DT bridge	JXA-only in v1 (multi-bridge-ready abstraction)	ADR-002
Vector DB	ChromaDB embedded	ADR-003
Embedding	paraphrase-multilingual-MiniLM-L12-v2 (default), BAAI/bge-m3 opt-in	ADR-008
Cache	SQLite WAL	—
Tests	pytest + 4-tier strategy	ADR-005
Packaging	uv workspace + hatchling	—
Logging	structlog (JSON to stderr)	—
Distribution	pipx + .mcpb desktop extension	—

Minimum DT version: DEVONthink 4.0. DT3 is not supported — see ADR-007.

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Repository structure

.
├── apps/
│   ├── server/      MCP server (FastMCP, stdio in v1; HTTP+OAuth → v2)
│   └── sidecar/     RAG sidecar (ChromaDB + embeddings)
├── libs/
│   ├── adapter/     JXA bridge + cache + errors + JXA scripts
│   └── schemas/     Shared Pydantic v2 models (common, tools, audit, errors)
├── tests/
│   ├── unit/        Unit tests (202 tests)
│   ├── contract/    VCR-style replay against real DT4 captures (8 tests)
│   ├── integration/ Real-DT smoke + latency benchmark (7 tests, opt-in)
│   └── benchmark/   Micro-benchmarks (opt-in)
├── docs/
│   └── adr/         Architecture decision records
├── .github/workflows/   CI (Ubuntu) + Integration (macOS-14) + Release (manual) + Publish-Registry
├── scripts/             build_mcpb.sh + smoke_e2e.sh
├── server.json          MCP Registry manifest
├── manifest.json        .mcpb bundle manifest
├── pyproject.toml       uv workspace + ruff + black + mypy + pytest
├── CLAUDE.md            Mandatory project constraints
├── memory.md            Decisions + context
└── handoff.md           Session-to-session handover

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Setup

# Prerequisites: macOS, DEVONthink 4 installed

# Install uv (if missing — alternative: brew install uv)
curl -LsSf https://astral.sh/uv/install.sh | sh

# Clone + sync workspace
git clone https://github.com/istefox/istefox-dt-mcp.git
cd istefox-dt-mcp
uv sync --all-packages

macOS Automation permission (mandatory)

DEVONthink only responds to Apple Events from apps that have explicit permission. On the first uv run istefox-dt-mcp doctor with DT running, macOS will show a "X wants to control DEVONthink" dialog: click OK.

If you don't see the dialog (because you clicked "Don't Allow" earlier):

1. Open System Settings → Privacy & Security → Automation.
2. Find the terminal or app you're running from (Warp, iTerm, Terminal, Claude Desktop).
3. Enable the toggle for DEVONthink.

Typical error when permission is denied: PERMISSION_DENIED with AppleScript code -1743. The connector intercepts it and suggests the affected app in the recovery_hint.

If your terminal doesn't appear in the Automation list, try tccutil reset AppleEvents <bundle-id> (e.g. com.apple.Terminal, com.googlecode.iterm2) and re-run the probe so macOS can prompt fresh.

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Quick start

# Lint + format check
uv run ruff check .
uv run black --check .

# Unit + contract tests (~6s)
uv run pytest tests/unit tests/contract -v

# Tests with coverage
uv run pytest tests/unit --cov=apps --cov=libs --cov-report=term

# Integration tests against real DT (opt-in; requires DT running + AppleEvents)
uv run pytest tests/integration -m integration --benchmark-enable -v

# Micro-benchmarks (opt-in: cache + bridge overhead)
uv run pytest tests/benchmark --benchmark-enable --benchmark-only

# CLI
uv run istefox-dt-mcp --help
uv run istefox-dt-mcp doctor       # health check (requires DT running)
uv run istefox-dt-mcp serve        # stdio server (for Claude Desktop)
uv run istefox-dt-mcp audit list --recent 5   # last 5 audit entries

# VCR cassette recording (developer-only, requires DT4 + fixtures-dt-mcp DB)
# See docs/development/cassette-recording.md
uv run istefox-dt-mcp record-cassette --tool search_bm25
uv run istefox-dt-mcp record-cassette --all   # auto-resets DB to manifest baseline first

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Testing

Unit, contract, and integration tests use pytest. For details on capturing new VCR cassettes from a live DEVONthink instance, see docs/development/cassette-recording.md.

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Performance tuning (env vars)

Variable	Default	Effect
ISTEFOX_FAST_LIST_DATABASES	false	If truthy (1/true/yes/on): list_databases skips computing record_count (returns null). Useful on databases with tens of thousands of records, where d.contents().length can take seconds on the first call (the 5-min cache amortizes subsequent calls). Default: count included, behavior unchanged.
ISTEFOX_PREVIEW_TTL_S	300	Override TTL in seconds for preview_token (default 5 minutes). Valid range: 1–3600.
ISTEFOX_RAG_ENABLED	false	If truthy: enables the vector RAG provider (see next section).
ISTEFOX_RAG_MODEL	paraphrase-multilingual-MiniLM-L12-v2	Override the embedding model (e.g. BAAI/bge-m3). Only used when RAG is enabled.

For .mcpb installs (Claude Desktop): since v0.0.22 these four variables are configurable from the Claude Desktop UI without editing files. Open Settings → Extensions → istefox-dt-mcp → Configure and you'll see a form with human-readable labels for each option. Edit + Save + restart the server.

For pipx/dev installs: set the env vars in your shell profile (~/.zshrc) or in the launch command.

RAG (vector search) — opt-in experimental

⚠️ Experimental: the RAG code is complete and unit-tested, but the embedding model default has not been validated cross-corpus yet. See ADR-008 for the criteria to flip the default to bge-m3 in a future release (target 0.4.0+). If you enable RAG now, be aware that quality depends heavily on your corpus — feedback via GitHub issues is very welcome.

The server runs in BM25-only mode by default (zero overhead, no models to download). To enable vector search:

# 1. Enable the RAG provider (env var)
export ISTEFOX_RAG_ENABLED=1

# 2. (Optional) Override the model — default is MiniLM-L12-v2
export ISTEFOX_RAG_MODEL=BAAI/bge-m3   # ~2.2 GB, higher quality

# 3. Index a DT database (one-shot — automatic sync covered below)
uv run istefox-dt-mcp reindex <your-database-name>
uv run istefox-dt-mcp reindex <your-database-name> --limit 100   # partial test

# 4. Verify the index
uv run istefox-dt-mcp doctor
# {... "rag": {"indexed_count": N, "embedding_model": "..."}}

# 5. Start the server and use search mode=hybrid or ask_database
uv run istefox-dt-mcp serve

ChromaDB is embedded and persisted at ~/.local/share/istefox-dt-mcp/vectors/. Lazy load: the model is downloaded/loaded on the first call to search or ask_database in semantic mode, not at startup.

Automatic sync (opt-in)

For real-time incremental indexing via DT4 smart rules + periodic reconciliation:

# 1. (Optional) generate a webhook token
export ISTEFOX_WEBHOOK_TOKEN="$(openssl rand -hex 16)"

# 2. Start the daemon
uv run istefox-dt-mcp watch \
    --port 27205 \
    --databases <your-database-name> \
    --reconcile-interval-s 21600   # every 6h

# 3. Configure the DT4 smart rule (see docs/smart-rules/sync_rag.md)
# 4. Manual reconciliation now and then:
uv run istefox-dt-mcp reconcile <your-database-name>

For auto-start at boot: see docs/smart-rules/sync_rag.md §"launchd auto-start".

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Claude Desktop integration (dev)

For end users, see Quick Install. This section covers the dev workflow (bundle build and manual config for source installs).

Build the .mcpb bundle (only requires bash + zip + unzip):

./scripts/build_mcpb.sh
# Output: dist/istefox-dt-mcp-<version>.mcpb (~290 KB)

The bundle uses server.type=python with a bash wrapper (bundle_main.sh) that detects uv across common install locations (Homebrew, cargo, pipx, mise, asdf, plus the ISTEFOX_UV_BIN override). Claude Desktop manages the runtime lifecycle.

Manual claude_desktop_config.json (source install):

{
  "mcpServers": {
    "istefox-dt-mcp": {
      "command": "uv",
      "args": ["--directory", "/path/to/istefox-dt-mcp", "run", "istefox-dt-mcp", "serve"]
    }
  }
}

Path: ~/Library/Application Support/Claude/claude_desktop_config.json. Restart Claude Desktop. All six tools become available.

RAG and other options: via env vars in the process that launches claude (manual config) or via the Settings → Extensions → Configure UI for the bundle (since v0.0.22).

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Key documents

File	Contents
CLAUDE.md	Mandatory project constraints (legal, MCP, DT, safety)
memory.md	Consolidated decisions + open questions + context
handoff.md	Current state + next steps
docs/architecture.md	Layered overview of the solution
docs/adr/	Architecture decision records (stack, bridge, sidecar, MVP, tests, DT4, RAG model)
docs/adr/REVIEW_ADR.md	Architecture review v1.0 (input to the formal ADRs)
ARCH-BRIEF-DT-MCP.md	Original architecture brief v0.1 (historical source of truth)

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Legal constraints

• Clean-room implementation: no code copied from dvcrn/mcp-server-devonthink (GPL-3.0).
• Privacy by design: no user data leaves the machine by default. Embeddings are generated locally; the audit log is local.
• Personal namespace: istefox (this is a personal project, not a work project).

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Other MCP servers by istefox

• obsidian-mcp-connector — community-continuation fork of jacksteamdev/obsidian-mcp-tools. In-process Streamable HTTP MCP server inside Obsidian (no native binary), 20 tools over your vault, native semantic search via Transformers.js. MIT.

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License

MIT License © 2026 Stefano Ferri.

You may use, modify, and redistribute the code (including commercially) as long as you keep the copyright notice. See LICENSE for the full text.