MCP Memory Server: Complete Guide to Persistent AI Memory

What is an MCP Memory Server?

An MCP memory server is a local service that implements the Model Context Protocol (MCP) to provide AI coding agents with persistent memory. Instead of losing context between sessions, your agent stores decisions, patterns, and bugs in a searchable memory store.

toon-memory is the most complete MCP memory server available:

• 35 MCP tools + 4 resources
• 15+ agent support — Claude, Cursor, OpenCode, and more
• Token-efficient format — 22% fewer tokens than JSON
• Graph-aware recall — BM25 + centrality + quality scoring
• Zero config — install and use

How MCP Memory Servers Work

The Model Context Protocol

MCP (Model Context Protocol) is a standard for AI agents to communicate with external tools. An MCP memory server:

1. Receives requests from the agent via stdio
2. Processes memory operations (save, search, delete)
3. Stores data locally in a structured format
4. Returns results formatted for the agent

Architecture

Your AI Agent
    ↓ MCP Protocol (stdio)
Memory Server (toon-memory)
    ↓
Local File (.toon-memory/memory/data.toon)

No cloud. No API calls. No network. Everything stays on your machine.

Why Use an MCP Memory Server?

The Problem

AI coding agents have no memory between sessions:

• Claude forgets the architecture decisions from yesterday
• Cursor can’t recall the bug fixes you discovered
• OpenCode doesn’t remember the patterns your team established

This wastes tokens, burns time, and leads to frustrating repetition.

The Solution

An MCP memory server gives your agent persistent memory:

Without MCP Memory	With MCP Memory
Re-explain context every session	Context persists automatically
2,411 tokens per session	972 tokens per session (-60%)
25 tool calls per session	5 tool calls per session (-80%)
$0.072 per session (GPT-4)	$0.029 per session (-60%)

MCP Memory Server Features

34 MCP Tools

toon-memory exposes 35 MCP tools for full memory management:

Core Tools:

• memory_remember — Save decisions, patterns, bugs, knowledge
• memory_recall — Search memory (flat or graph mode)
• memory_smart_recall — Unified recall with BM25 + graph + quality
• memory_forget — Remove entries
• memory_stats — View memory state

Context Tools:

• context_brief — One-call context briefing
• context_generate — Full project briefing
• context_diff — What changed since last session
• context_focus — Hyper-focused briefing
• context_health — Memory health audit
• context_export — Export as markdown

Management Tools:

• memory_summary — Save/retrieve file summaries
• memory_archive — Archive old entries
• memory_diff — Show changes since date
• memory_suggest — Find related entries
• memory_sessions — Multi-session coordination
• memory_captured — View hook-captured activity
• memory_consolidate — Merge duplicates
• memory_encrypt — AES-256-GCM encryption
• memory_decrypt — Disable encryption

Token-Efficient Format

Memory is stored in TOON format (Token-Oriented Object Notation):

a1b2c3d4|decision|use-zod|Use Zod for validation|src/types.ts|validation;types|2026-07-10

22% fewer tokens than equivalent JSON, designed for LLM comprehension.

Graph-Aware Recall

Entries are connected via explicit links and implicit references:

memory_remember({
  category: "decision",
  key: "use-redis",
  content: "Use Redis for session storage (see [[redis-config]])",
  links: "redis-config"
})

Recall expands the ego-subgraph to find related entries, even if they don’t contain the exact search term.

Quality Scoring

Every entry gets an automatic quality score (0-1):

Factor	Weight
Tags	0.3 max
Links	0.2 max
Content length	0.3 max
Recency	0.1 max
Specificity	0.1 max

High-quality entries surface first in recall.

Setup Guide

Step 1: Install

npm install -g toon-memory

Step 2: Configure

npx toon-memory  # Interactive installer

Or manually add to your agent’s MCP config:

{
  "mcpServers": {
    "toon-memory": {
      "command": "npx",
      "args": ["-y", "toon-memory", "mcp"]
    }
  }
}

Step 3: Use

# Save important decisions
memory_remember({
  category: "decision",
  key: "use-postgres",
  content: "Choose Postgres for ACID compliance"
})

# Search memory
memory_recall({ query: "database" })

# Get full context in one call
memory_smart_recall({ intent: "what I was working on" })

Benchmarks

Token Efficiency

Format          Tokens (16 entries)    vs JSON
──────────────  ───────────────────    ───────
JSON            1097                   baseline
TOON            850                    -22.5%

Recall Efficiency

Method                          Tokens to get context    vs re-reading files
─────────────────────────────  ─────────────────────    ───────────────────
Re-read source files            ~3000                    baseline
memory_recall (flat)            ~1200                    -60%
memory_recall (graph, compact)  ~900                     -70%
memory_smart_recall             ~850                     -72%

Context Tools Benchmark

Scenario                          Without   With    Saved    Tools
────────────────────────────────  ────────  ──────  ───────  ──────
context_generate (full briefing)    5,556     378    93.2%   6 → 1
context_diff (incremental)            533     152    71.5%   4 → 1
context_focus (targeted)              413     225    45.5%   4 → 1
context_health (audit)                322     246    23.6%   5 → 1
context_export (injectable md)      1,178     218    81.5%   3 → 1
────────────────────────────────  ────────  ──────  ───────  ──────
TOTAL                              8,002   1,219    84.8%  22 → 5

Supported Agents

toon-memory works with 15+ AI coding agents:

• OpenCode, Claude Code, Cursor, Windsurf, VS Code Copilot
• Codex CLI, Gemini CLI, Zed, Cline, Continue
• Antigravity, Aider, KiloCode, OpenClaw, Kiro

See the Supported Agents page for configuration details.

Conclusion

An MCP memory server gives your AI coding agent the persistent memory it needs to be truly productive. toon-memory is the most complete solution available:

• 35 MCP tools for full memory management
• Token-efficient format that saves 22% on every session
• Graph-aware recall that finds related context automatically
• 15+ agent support with zero-config setup

npm install -g toon-memory
npx toon-memory  # Interactive installer

Your agent will remember everything in the next session.