yantrikdb-mcp 0.8.0

YantrikDB MCP Server — Cognitive memory for AI agents

YantrikDB MCP Server

Cognitive memory for AI agents. Works with Claude Code, Cursor, Windsurf, and any MCP-compatible client.

Website: yantrikdb.com · Docs: yantrikdb.com/guides/mcp · GitHub: yantrikos/yantrikdb-mcp

Install

# Default — uses the engine's bundled 64-dim embedder. ~10 MB install,
# ~80 ms cold start, no native ML deps.
pip install yantrikdb-mcp

# Optional: higher-quality 384-dim ONNX MiniLM-L6-v2 embedder (~150 MB install).
# Auto-used when an existing pre-v0.6 database is detected.
pip install 'yantrikdb-mcp[onnx]'

Upgrading from v0.5.x? Your existing database stays at 384 dim — install the [onnx] extra to keep using it transparently. New installs default to the lean bundled embedder. v0.7.0+ pins the engine migration fix automatically. See Embedder backends below.

Configure

The MCP server has three deployment modes. Pick the one that fits your setup.

Mode 1 — Local (default, recommended for single user)

The MCP server runs the engine in-process with a local SQLite database. Fast, private, zero dependencies.

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

That's it. The agent auto-recalls context, auto-remembers decisions, and auto-detects contradictions — no prompting needed.

Mode 2 — HTTP Cluster (recommended for shared/multi-machine setups)

Forward all tool calls to a YantrikDB HTTP cluster instead of using an embedded engine. The MCP server is a thin stateless client — all memories live on the cluster, accessible from any machine.

Benefits: shared memory across machines, high availability, no local embedder download, no local database.

{
  "mcpServers": {
    "yantrikdb": {
      "command": "yantrikdb-mcp",
      "env": {
        "YANTRIKDB_SERVER_URL": "http://node1:7438,http://node2:7438",
        "YANTRIKDB_TOKEN": "ydb_your_database_token"
      }
    }
  }
}

• Comma-separate multiple nodes for Raft cluster auto-discovery
• Automatic leader-following on failover
• 15s request timeout
• Get the token from the cluster: yantrikdb token create --db your_database

Mode 3 — SSE Server (legacy, single remote instance)

Run the MCP server itself as a long-running SSE server with its own embedded database. Clients connect via HTTP streaming.

# Generate a secure API key
export YANTRIKDB_API_KEY=$(python -c "import secrets; print(secrets.token_urlsafe(32))")

# Start SSE server
yantrikdb-mcp --transport sse --port 8420

{
  "mcpServers": {
    "yantrikdb": {
      "type": "sse",
      "url": "http://your-server:8420/sse",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

Supports sse and streamable-http transports. Note: SSE connections can drop on idle — Mode 2 (HTTP Cluster) is more reliable for shared deployments.

Environment Variables

Variable	Used in Mode	Default	Description
YANTRIKDB_SERVER_URL	Cluster	(unset → local mode)	Comma-separated cluster node URLs
YANTRIKDB_TOKEN	Cluster	(none)	Bearer token for the cluster database
YANTRIKDB_DB_PATH	Local	~/.yantrikdb/memory.db	Database file path
YANTRIKDB_EMBEDDER	Local	auto	Backend selector: auto | bundled | onnx | multilingual
YANTRIKDB_EMBEDDING_MODEL	Local	all-MiniLM-L6-v2	ONNX model name (only used when YANTRIKDB_EMBEDDER=onnx)
YANTRIKDB_SKILLS_WRITE_ENABLED	All	false	Set true to allow agents to author skills (see Skill substrate below)
YANTRIKDB_API_KEY	SSE server	(none)	Bearer token when serving SSE/HTTP

Embedder backends

Local mode ships three embedders. The MCP picks one automatically; override with YANTRIKDB_EMBEDDER.

Backend	Dim	Cold start	Install size	Language coverage	When it's used
bundled (engine default)	64	~80 ms	~10 MB	English-only	New / empty databases (auto-selected)
onnx (MiniLM-L6-v2)	384	~2 s	~150 MB	English (higher recall)	Existing pre-v0.6 databases (auto-selected), or when set explicitly
multilingual (potion-multilingual-128M)	256	~2 s + ~460 MB download on first use	~10 MB pip + ~500 MB model cache	101 languages (BGE-M3 tokenizer)	Opt-in only via YANTRIKDB_EMBEDDER=multilingual

auto (default) reads the SQLite file at YANTRIKDB_DB_PATH and picks onnx if it already contains memories — preserving recall quality on upgrades — and bundled otherwise. Multilingual is never auto-selected because its 256-dim vectors are incompatible with existing bundled (64-dim) or ONNX (384-dim) databases; opt-in only on fresh databases.

Set YANTRIKDB_EMBEDDER=bundled|onnx|multilingual to override. If you set YANTRIKDB_EMBEDDER=onnx (or auto-detection picks it) without installing the extras, the server fails fast with an install hint:

RuntimeError: Existing DB has memories embedded with the 384-dim ONNX
model, but ONNX deps are missing.
  Install with:  pip install 'yantrikdb-mcp[onnx]'

For the multilingual backend, the engine downloads potion-multilingual-128M (~460 MB tarball) from github.com/yantrikos/yantrikdb-models on first use. The download is SHA-256 verified, extracted into the engine's cache dir, and reused on subsequent starts. No extra Python deps required — the model runs entirely inside the Rust engine.

Why Not File-Based Memory?

File-based memory (CLAUDE.md, memory files) loads everything into context every conversation. YantrikDB recalls only what's relevant.

Benchmark: 15 queries × 4 scales

Memories	File-Based	YantrikDB	Savings	Precision
100	1,770 tokens	69 tokens	96%	66%
500	9,807 tokens	72 tokens	99.3%	77%
1,000	19,988 tokens	72 tokens	99.6%	84%
5,000	101,739 tokens	53 tokens	99.9%	88%

Selective recall is O(1). File-based memory is O(n).

• At 500 memories, file-based exceeds 32K context windows
• At 5,000, it doesn't fit in any context window — not even 200K
• YantrikDB stays at ~70 tokens per query, under 60ms latency
• Precision improves with more data — the opposite of context stuffing

Run the benchmark yourself: python benchmarks/bench_token_savings.py

Tools

16 tools, full engine coverage:

Tool	Actions	Purpose
remember	single / batch	Store memories — decisions, preferences, facts, corrections
recall	search / refine / feedback	Semantic search, refinement, and retrieval feedback
forget	single / batch	Tombstone memories
correct	—	Fix incorrect memory (preserves history)
think	—	Consolidation + conflict detection + pattern mining
memory	get / list / search / update_importance / archive / hydrate	Manage individual memories + keyword search
graph	relate / edges / link / search / profile / depth	Knowledge graph operations
conflict	list / get / resolve / reclassify	Handle contradictions and teach substitution patterns
trigger	pending / history / acknowledge / deliver / act / dismiss	Proactive insights and warnings
session	start / end / history / active / abandon_stale	Session lifecycle management
temporal	stale / upcoming	Time-based memory queries
procedure	learn / surface / reinforce	Procedural memory — learn and reuse strategies
category	list / members / learn / reset	Substitution categories for conflict detection
personality	get / set	AI personality traits from memory patterns
stats	stats / health / weights / maintenance	Engine stats, health, weights, and index rebuilds
skill	define / surface / outcome / get / list	Substrate-native agent skill catalog (writes off by default — see Skill substrate)

See yantrikdb.com/guides/mcp for full documentation.

Skill substrate (v0.8.0+)

YantrikDB exposes a structured agent skill catalog — separate from loose procedure memories. Skills have schema (skill_id, applies_to, triggers, body, type) and are stored in the dedicated skill_substrate namespace so multiple consumers (this MCP, yantrikdb-hermes-plugin, Lane B SDK, WisePick, yantrikdb-server's /v1/skills/* endpoints) all read and write the same substrate. Background: Sarkar 2026 — Skill as Memory, Not Document.

Security model

Skill writes shape future agent behavior across sessions, so the MCP server implements defense-in-depth. Every control has an env-var knob (locked once at startup — C2) and the full state is exposed via stats(action="stats") and the audit log.

Layered controls (each ships on by default unless noted):

Layer	Control	Env var	Notes
Schema	skill_id regex, body 50–5000 chars, applies_to 1–10 entries, skill_type enum	(always on)	Same regex set as yantrikdb-server /v1/skills/define
A1 Prompt-injection markers	Reject bodies containing role-confusion / "ignore previous instructions" patterns	YANTRIKDB_SKILLS_DISABLE_SCANNERS=A1 to disable (audited)	OWASP LLM01
A2 Credential scanner	AWS/GitHub/Slack/Stripe/Google/Anthropic/OpenAI keys, SSH/PGP private keys, JWT, password assignments	=A2 to disable	Subset of GitHub secret-scanning
A3 URL/IP block	Reject http(s), ftp, IPv4 literals in body	YANTRIKDB_SKILLS_ALLOW_URLS=true to allow	Exfil path for downstream agents
A4 Unicode evasion	Reject non-printing chars (Cf/Cs/Cn except whitelisted)	=A4 to disable	Bidi override (U+202E), zero-width spaces
A5 Encoded payload	Reject ≥200-char runs of base64/hex	=A5 to disable	Heuristic — false-positive prone for large hashes
B1 Namespace allowlist	skill_id first segment must be in operator list	YANTRIKDB_SKILLS_ALLOWED_NAMESPACES=workflow,review	Unset = all allowed
B2 Author attribution	Records session_id, os_user, hostname, wall_clock, audit_nonce	(always on)	Forensic trail
B3 Cross-origin replace	Refuse to overwrite a skill written by a different consumer	YANTRIKDB_SKILLS_ALLOW_CROSS_ORIGIN_REPLACE=true to allow	Defends against MCP↔hermes-plugin collision
B4 Supersedes integrity	supersedes must reference an existing skill in the same namespace	(always on)	Blocks malicious retirement of legit skills
C1 Time-bound gate	Gate auto-closes at the timestamp	YANTRIKDB_SKILLS_WRITE_EXPIRES_AT=2026-12-31T00:00:00Z	Unset = no expiry
C2 Locked config	All YANTRIKDB_SKILLS_* env vars read once at startup	(always on)	Mutating env in a sub-process can't bypass the gate
D1 Audit log	JSONL append of every accept/reject/tamper event	YANTRIKDB_SKILLS_AUDIT_LOG=/var/log/yantrikdb/skills.jsonl	Unset = no auditing (warns at boot)
D2 Rate limit	Per-session-id sliding-window write cap	YANTRIKDB_SKILLS_WRITE_RATE=30 (default writes/min)	Defeats flood attacks
D3 Outcome.note guards	Note ≤500 chars + scanned by A1/A2/A4	(always on)	Closes the outcome side-channel
D4 Counters in stats	Accept/reject counts by reason, surfaced in stats(action="stats")["skill_substrate"]	(always on)	Operator dashboards
E1 Body SHA-256	Stored at write time, re-verified on every read	(always on)	Detects out-of-band DB tampering — surface/get omit mismatches and log to audit
E2 Author origin	metadata.author_origin tag — defaults to yantrikdb-mcp	YANTRIKDB_SKILLS_AUTHOR_ORIGIN=... to override	Tracks substrate provenance across consumers
F Startup safety	Boot-time warnings about dangerous configurations	(always on)	Logs [F.1]–[F.5] to stderr + audit
G Review queue for rule	rule-type skills route to skill_pending_review (not surfaced by surface/get/list)	YANTRIKDB_SKILLS_RULE_REQUIRES_REVIEW=false to disable (not recommended)	Rules influence agent policy — human approval required
Multi-tenant guard	[F.1] warning if DB shows multiple actor IDs without ack	YANTRIKDB_SKILLS_MULTITENANT_ACK=true	One DB = one tenant is the safe default

Enterprise checklist:

# Minimum production config when you turn the gate ON:
YANTRIKDB_SKILLS_WRITE_ENABLED=true
YANTRIKDB_SKILLS_WRITE_EXPIRES_AT=2026-12-31T00:00:00Z
YANTRIKDB_SKILLS_ALLOWED_NAMESPACES=workflow,review,onboarding
YANTRIKDB_SKILLS_AUDIT_LOG=/var/log/yantrikdb/skills.audit.jsonl
YANTRIKDB_SKILLS_AUTHOR_ORIGIN=acme-corp-claude-prod
# Defaults are already correct: writes off, scanners on, rate-limit 30/min,
# rule-type routed to review, body-hash verified on read, locked at startup.

The audit log is the canonical record. Every accept, every reject (with the scanner that flagged), every tamper-detection on read, every gate-closed-due-to-expiry — all there in JSONL. Plug it into your SIEM.

stats(action="stats") example output (skill_substrate slice)

"skill_substrate": {
  "counters": {
    "skill_defines_accepted": 12,
    "skill_defines_rejected": {"content_scan:A2": 1, "namespace_not_allowed": 3},
    "skill_outcomes_recorded": 47,
    "skill_pending_review": 2
  },
  "config": {
    "writes_enabled": true,
    "write_expires_at": "2026-12-31T00:00:00+00:00",
    "allowed_namespaces": ["workflow", "review"],
    "audit_log_path": "/var/log/yantrikdb/skills.audit.jsonl",
    "rule_requires_review": true,
    "author_origin": "acme-corp-claude-prod"
  }
}

Schema (validated at write time)

Field	Constraint
skill_id	Lowercase dot-separated segments, length 4–200, e.g. workflow.git.commit_clean
body	50–5000 chars
applies_to	1–10 lowercase-underscore identifiers (no hyphens — load-bearing for substrate consistency)
skill_type	One of procedure, reference, lesson, pattern, rule
on_conflict	reject (default) or replace

Example session

# Define (requires gate enabled)
skill(action="define",
      skill_id="workflow.git.commit_clean",
      body="Before commit: run pytest, run lint, write a clear subject + body.",
      skill_type="procedure",
      applies_to=["git", "release"])

# Surface relevant skills for the current task
skill(action="surface", query="how to commit cleanly", top_k=5)

# Record an outcome after using the skill (gated, append-only)
skill(action="outcome", skill_id="workflow.git.commit_clean",
      succeeded=True, note="caught a flake8 issue pre-push")

Outcomes are append-only events in the outcome_substrate namespace — no auto-rollup on the parent skill, matching yantrikdb-server's "schema not semantics" design rule. Agents (or the operator) can aggregate outcomes themselves to compute success rates.

Examples

1. Auto-recall at conversation start

User: "What did we decide about the database migration?"

The agent automatically calls recall("database migration decision") and retrieves relevant memories before responding — no manual prompting needed.

2. Remember decisions + build knowledge graph

User: "We're going with PostgreSQL for the new service. Alice will own the migration."

The agent calls:

• remember(text="Decided to use PostgreSQL for the new service", domain="architecture", importance=0.8)
• remember(text="Alice owns the PostgreSQL migration", domain="people", importance=0.7)
• graph(action="relate", entity="Alice", target="PostgreSQL Migration", relationship="owns")

3. Contradiction detection

After storing "We use Python 3.11" and later "We upgraded to Python 3.12", calling think() detects the conflict. The agent surfaces it:

"I found a contradiction: you previously said Python 3.11, but recently mentioned Python 3.12. Which is current?"

Then resolves with conflict(action="resolve", conflict_id="...", strategy="keep_b").

Privacy Policy

YantrikDB MCP Server stores all data locally on your machine (default: ~/.yantrikdb/memory.db). No data is sent to external servers, no telemetry is collected, and no third-party services are contacted during operation.

• Data collection: Only what you explicitly store via the remember tool or what the AI agent stores on your behalf.
• Data storage: Local SQLite database on your filesystem. You control the path via YANTRIKDB_DB_PATH.
• Third-party sharing: None. Data never leaves your machine in local (stdio) mode.
• Network mode: When using SSE/HTTP transport, data travels between your client and your self-hosted server. No Anthropic or third-party servers are involved.
• Embedding model: Uses a local ONNX model (all-MiniLM-L6-v2). Model files are downloaded once from Hugging Face Hub on first use, then cached locally.
• Retention: Data persists until you delete it (forget tool) or delete the database file.
• Contact: [e-mail]

Full policy: yantrikdb.com/privacy

Contributing

See CONTRIBUTING.md for a venv setup, running pytest, and opening PRs.

Support

• Issues: github.com/yantrikos/yantrikdb-mcp/issues
• Email: [e-mail]
• Docs: yantrikdb.com/guides/mcp

License

This MCP server is licensed under MIT — use it freely in any project.

Note: This package depends on yantrikdb (the cognitive memory engine), which is licensed under AGPL-3.0. The AGPL applies to the engine itself — if you modify the engine and distribute it or provide it as a network service, those modifications must also be AGPL-3.0. Using the engine as-is via this MCP server does not trigger AGPL obligations on your code.