mnemon-mcp

Persistent layered memory for AI agents. Local-first. Zero-cloud. Single SQLite file.

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Your AI agent forgets everything after each session. Mnemon fixes that.

It gives any MCP-compatible client — OpenClaw, Claude Code, Cursor, Windsurf, or your own — a structured long-term memory backed by a single SQLite database on your machine. No API keys, no cloud, no telemetry. Just npm install and your agent remembers.

Why Layered Memory?

Flat key-value stores treat "what happened yesterday" the same as "never commit without tests." That's wrong — different kinds of knowledge have different lifetimes and access patterns.

Mnemon organizes memories into four layers:

| Layer | What it stores | How it's accessed | Lifetime | |-------|---------------|-------------------|----------| | Episodic | Events, sessions, journal entries | By date or period | Decays (30-day half-life) | | Semantic | Facts, preferences, relationships | By topic or entity | Stable | | Procedural | Rules, workflows, conventions | Loaded at startup | Rarely changes | | Resource | Reference material, book notes | On demand | Decays slowly (90 days) |

A journal entry from last Tuesday and a coding rule that never changes live in different layers — because they should.

Quick Start

Install

npm install -g mnemon-mcp

Or from source:

git clone https://github.com/nikitacometa/mnemon-mcp.git
cd mnemon-mcp && npm install && npm run build

Configure Your MCP Client

openclaw mcp register mnemon-mcp --command="mnemon-mcp"

Or add to ~/.openclaw/mcp_config.json:

{
  "mnemon-mcp": {
    "command": "mnemon-mcp"
  }
}

Add to ~/.claude/mcp.json:

{
  "mcpServers": {
    "mnemon-mcp": {
      "command": "mnemon-mcp"
    }
  }
}

Add to your client's MCP config:

{
  "mcpServers": {
    "mnemon-mcp": {
      "command": "mnemon-mcp"
    }
  }
}

Use the full path to the compiled entry point:

{
  "mnemon-mcp": {
    "command": "node",
    "args": ["/absolute/path/to/mnemon-mcp/dist/index.js"]
  }
}

Verify

echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | mnemon-mcp

You should see 10 tools in the response. The database (~/.mnemon-mcp/memory.db) is created automatically on first run.

That's it. Your agent now has persistent memory.

What It Can Do

10 MCP Tools

| Tool | What it does | |------|-------------| | memory_add | Store a memory with layer, entity, confidence, importance, and optional TTL | | memory_search | Full-text or exact search with filters by layer, entity, date, scope, confidence | | memory_update | Update in-place or create a versioned replacement (superseding chain) | | memory_delete | Delete a memory; re-activates its predecessor if any | | memory_inspect | Get layer statistics or trace a single memory's version history | | memory_export | Export to JSON, Markdown, or Claude-md format with filters | | memory_health | Run diagnostics: expired entries, orphaned chains, stale memories; optionally GC | | memory_session_start | Start an agent session — returns session ID for grouping memories | | memory_session_end | End a session with optional summary; returns duration and memory count | | memory_session_list | List sessions with filters by client, project, or active status |

MCP Resources & Prompts

Resources — live data your agent can read:

| URI | Returns | |-----|---------| | memory://stats | Aggregate stats per layer | | memory://recent | Memories created/updated in last 24h | | memory://layer/{layer} | All active memories in a layer | | memory://entity/{name} | All active memories about an entity |

Prompts — pre-built workflows:

| Prompt | Purpose | |--------|---------| | recall | "Tell me everything you know about X" | | context-load | Load relevant context before starting a task | | journal | Create a structured journal entry |

Search

Four modes, all supporting layer / entity / scope / date / confidence filters:

FTS mode (default without embeddings) — tokenized full-text search with BM25 ranking. Multi-word queries use AND; if too few results, OR supplements with a score penalty. Progressive AND relaxation tries top-3 most specific terms before falling back to full OR.

Hybrid mode (default when embeddings configured) — combines FTS5 + vector search via Reciprocal Rank Fusion. Detects quoted entities in queries (e.g., 'Essentialism') and runs weighted sub-queries for cross-reference retrieval.

Vector mode — pure cosine similarity search over embeddings.

Exact mode — LIKE substring match for precise phrase lookups.

Scores: bm25 × (0.3 + 0.7 × importance) × decay(layer) × recency

Recency boost: 1 / (1 + daysSince / 365) — gently rewards recently created memories without penalizing old ones.

Stemming

Snowball stemmer applied at both index time and query time for English and Russian. This means "running" matches "runs", and "книги" matches "книга". Stop words are filtered from queries to improve precision.

Fact Versioning

Knowledge evolves. Mnemon doesn't delete old facts — it chains them:

v1: "Team uses React 17"  →  superseded_by: v2
v2: "Team uses React 19"  →  supersedes: v1 (active)

Search returns only the latest version. memory_inspect with include_history: true reveals the full chain. memory_delete re-activates the predecessor — nothing is lost.

Vector Search (Optional, BYOK)

Enable semantic similarity search by providing your own embedding API:

# OpenAI
MNEMON_EMBEDDING_PROVIDER=openai MNEMON_EMBEDDING_API_KEY=sk-... mnemon-mcp

# Ollama (local, free)
MNEMON_EMBEDDING_PROVIDER=ollama mnemon-mcp

This unlocks two additional search modes:

• mode: "vector" — pure cosine similarity search
• mode: "hybrid" — FTS5 + vector combined via Reciprocal Rank Fusion

Requires sqlite-vec (installed as optional dependency). New memories are embedded on add; existing ones can be backfilled.

| Variable | Default | Description | |----------|---------|-------------| | MNEMON_EMBEDDING_PROVIDER | — | openai or ollama (unset = disabled) | | MNEMON_EMBEDDING_API_KEY | — | API key (required for OpenAI) | | MNEMON_EMBEDDING_MODEL | text-embedding-3-small / nomic-embed-text | Model name | | MNEMON_EMBEDDING_DIMENSIONS | 1024 / 768 | Vector dimensions | | MNEMON_OLLAMA_URL | http://localhost:11434 | Ollama endpoint |

Importing a Knowledge Base

Got a folder of Markdown files? Import them in bulk:

cp config.example.json ~/.mnemon-mcp/config.json   # edit this first
npm run import:kb -- --kb-path /path/to/your/kb     # incremental (skips unchanged files)

The config maps glob patterns to memory layers:

{
  "owner_name": "your-name",
  "extra_stop_words": [],
  "mappings": [
    {
      "glob": "journal/*.md",
      "layer": "episodic",
      "entity_type": "user",
      "entity_name": "$owner",
      "importance": 0.6,
      "split": "h2"
    },
    {
      "glob": "people/*.md",
      "layer": "semantic",
      "entity_type": "person",
      "entity_name": "from-heading",
      "importance": 0.8,
      "split": "h3"
    }
  ]
}

Config Fields

| Field | Type | Description | |-------|------|-------------| | owner_name | string | Your name — used for $owner substitution in entity_name | | extra_stop_words | string[] | Words to filter from FTS queries (e.g., your name forms) | | glob | string | File pattern to match | | layer | string | Target memory layer | | entity_type | string | user / person / project / concept / file / rule / tool | | entity_name | string | Literal name, "$owner", or "from-heading" (extract from H2/H3) | | split | string | "whole" (one memory per file), "h2", or "h3" (split on headings) | | importance | number | 0.0–1.0, affects search ranking | | confidence | number | 0.0–1.0, filterable in search | | scope | string | Optional namespace |

HTTP Transport

For remote or multi-client setups:

MNEMON_AUTH_TOKEN=your-secret MNEMON_PORT=3000 npm run start:http

| Endpoint | Description | |----------|-------------| | POST /mcp | MCP JSON-RPC (Bearer auth if token set) | | GET /health | {"status":"ok","version":"..."} |

Rate limiting (100 req/min/IP by default), CORS headers, 1MB body limit, timing-safe auth, graceful shutdown on SIGTERM.

Configuration Reference

| Variable | Default | Description | |----------|---------|-------------| | MNEMON_DB_PATH | ~/.mnemon-mcp/memory.db | Database path | | MNEMON_KB_PATH | . | Knowledge base root for import | | MNEMON_CONFIG_PATH | ~/.mnemon-mcp/config.json | Import config path | | MNEMON_AUTH_TOKEN | — | Bearer token for HTTP transport | | MNEMON_PORT | 3000 | HTTP transport port | | MNEMON_CORS_ORIGIN | * | CORS Access-Control-Allow-Origin | | MNEMON_RATE_LIMIT | 100 | Max requests per minute per IP (0 = off) |

Tool Reference

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | content | string | Yes | Memory text (max 100K chars) | | layer | string | Yes | episodic / semantic / procedural / resource | | title | string | No | Short title (max 500 chars) | | entity_type | string | No | user / project / person / concept / file / rule / tool | | entity_name | string | No | Entity name for filtering | | confidence | number | No | 0.0–1.0 (default 0.8) | | importance | number | No | 0.0–1.0 (default 0.5) | | scope | string | No | Namespace (default global) | | source_file | string | No | Source file path — triggers auto-supersede of matching entries | | ttl_days | number | No | Auto-expire after N days | | valid_from / valid_until | string | No | Temporal fact window (ISO 8601) |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | query | string | Yes | Search text | | mode | string | No | fts (default), exact, vector, hybrid | | layers | string[] | No | Filter by layers | | entity_name | string | No | Filter by entity (supports aliases) | | scope | string | No | Filter by scope | | date_from / date_to | string | No | Date range (ISO 8601) | | as_of | string | No | Temporal fact filter — facts valid at this date | | min_confidence | number | No | Minimum confidence | | min_importance | number | No | Minimum importance | | limit | number | No | Max results (default 10, max 100) | | offset | number | No | Pagination offset |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | id | string | Yes | Memory ID | | content | string | No | New content | | title | string | No | New title | | confidence | number | No | New confidence | | importance | number | No | New importance | | supersede | boolean | No | true = versioned replacement; false (default) = in-place | | new_content | string | No | Content for superseding entry |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | id | string | Yes | Memory ID. Re-activates predecessor if part of a superseding chain |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | id | string | No | Memory ID (omit for aggregate stats) | | layer | string | No | Filter stats by layer | | entity_name | string | No | Filter stats by entity | | include_history | boolean | No | Show superseding chain |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | format | string | Yes | json / markdown / claude-md | | layers | string[] | No | Filter by layers | | scope | string | No | Filter by scope | | date_from / date_to | string | No | Date range | | limit | number | No | Max entries (default all, max 10K) |

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | cleanup | boolean | No | true = garbage-collect expired entries (default: report only) |

Returns: status (healthy / warning / degraded), per-layer stats, expired entries, orphaned chains, stale/low-confidence counts, cleaned count when cleanup=true.

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | client | string | Yes | Client identifier (e.g. claude-code, cursor, api) | | project | string | No | Project scope for this session | | meta | object | No | Additional session metadata |

Returns: id (session UUID), started_at (ISO 8601).

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | id | string | Yes | Session ID to end | | summary | string | No | Summary of what was accomplished (max 10K chars) |

Returns: id, ended_at, duration_minutes, memories_count.

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | limit | number | No | Max sessions (default 20, max 100) | | client | string | No | Filter by client | | project | string | No | Filter by project | | active_only | boolean | No | Only return sessions that haven't ended (default false) |

Returns: array of sessions with id, client, project, started_at, ended_at, summary, memories_count.

How It Compares

| | mnemon-mcp | mem0 | basic-memory | Engram | Anthropic KG | |---|---|---|---|---|---| | Architecture | SQLite FTS5 + vector | Cloud API + Qdrant | Markdown + vector | SQLite FTS5 | JSON file | | Memory structure | 4 typed layers | Flat | Flat | Flat + sessions | Graph | | Search | FTS5 + hybrid RRF | Semantic | Hybrid | FTS5 | Exact | | Fact versioning | Superseding chains | Partial | No | No | No | | Stemming | EN + RU (Snowball) | EN only | EN only | None | None | | Embeddings | BYOK (OpenAI / Ollama) | Built-in | FastEmbed | None | None | | Dependencies | 0 required | Qdrant, Neo4j | Python 3.12 | Go binary | None | | Cloud required | No | Yes | No | No | No | | Cost | Free | $19–249/mo | Free | Free | Free | | Setup | npm install -g | Docker + API keys | pip + deps | Go install | Built-in | | License | MIT | Apache 2.0 | AGPL | MIT | MIT |

Development

npm run dev        # run via tsx (no build step)
npm run build      # TypeScript → dist/
npm test           # vitest (229 tests)
npm run bench      # performance benchmarks
npm run db:backup  # backup database

Stack: TypeScript 5.9 (strict mode), better-sqlite3, @modelcontextprotocol/sdk, Snowball stemmer, Zod, vitest.

See CONTRIBUTING.md for code guidelines.

Design Principles

• Air-gapped — zero network calls, zero telemetry. Your memories stay on your machine.
• Single file — one SQLite database, zero ops, instant backup via file copy.
• Deterministic search — FTS5, not embeddings, is the default. Interpretable, reproducible, no GPU needed.
• Structured over flat — layers encode access patterns; superseding chains encode time.
• Minimal — 4 production dependencies. Works everywhere Node runs.

License

MIT