Nexo
NEXO Brain — Shared brain for AI agents. Persistent memory, semantic RAG, natural forgetting, metacognitive guard, trust scoring, 150+ MCP tools. Works with Claude Code, Codex, Claude Desktop & any MCP client. 100% local, open source, free.
What is Nexo?
Nexo is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to nexo brain — shared brain for ai agents. persistent memory, semantic rag, natural forgetting, metacognitive guard, trust scoring, 150+ mcp tools. works with claude code, codex, claude desktop & any mc...
NEXO Brain — Shared brain for AI agents. Persistent memory, semantic RAG, natural forgetting, metacognitive guard, trust scoring, 150+ MCP tools. Works with Claude Code, Codex, Claude Desktop & any MCP client. 100% local, open source, free.
This server falls under the Knowledge & Memory category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- NEXO Brain — Shared brain for AI agents. Persistent memory,
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx nexoConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use Nexo
NEXO Brain is a 100% local, open-source shared memory and cognition layer for AI agents that exposes 150+ MCP tools across 23 categories. It provides persistent semantic memory, durable workflow tracking, decision-making support, trust scoring, and metacognitive guardrails — all running locally on your machine and shared across Claude Code, Claude Desktop, and Codex simultaneously. Developers and power users who run multiple AI agents and want them to share context, learn from past sessions, and avoid repeated mistakes will find NEXO an essential infrastructure layer.
Prerequisites
- Node.js 18 or later with npm installed globally
- An MCP-compatible client: Claude Code, Claude Desktop, or Codex
- Sufficient local disk space (~500 MB) for the NEXO runtime at ~/.nexo
- Optional: OpenTelemetry endpoint for distributed tracing (OTEL_EXPORTER_OTLP_ENDPOINT)
Install NEXO Brain globally
Install the nexo-brain package globally via npm. This sets up the NEXO runtime in ~/.nexo and makes the 'nexo' CLI available.
npm install -g nexo-brainRun the NEXO doctor to verify your environment
Use the built-in diagnostics command to confirm NEXO is installed correctly, the runtime is healthy, and all dependencies are available.
nexo doctor --tier deepAdd NEXO to your Claude Code or Claude Desktop MCP configuration
Register NEXO as an MCP server in your AI client. The same runtime is shared across all clients automatically.
{
"mcpServers": {
"nexo": {
"command": "nexo",
"args": ["mcp"],
"env": {
"NEXO_HOME": "~/.nexo"
}
}
}
}Calibrate NEXO for your preferences and role
Edit the calibration file to set your language, role, and behavioral preferences. NEXO uses this to personalize memory consolidation and decision ranking.
# Edit ~/.nexo/brain/calibration.json with your preferences:
# {
# "language": "en",
# "role": "software-engineer",
# "preferences": {}
# }Start using memory and workflow tools in your AI sessions
NEXO tools are now available in your AI client. Agents can save lessons, open durable workflows, checkpoint progress, and recall past context semantically.
# Export your NEXO knowledge graph for backup:
nexo export --output bundle.json
# Import on a new machine:
nexo import --input bundle.jsonNexo Examples
Client configuration
Claude Desktop or Claude Code MCP configuration for the NEXO Brain server.
{
"mcpServers": {
"nexo": {
"command": "nexo",
"args": ["mcp"],
"env": {
"NEXO_HOME": "~/.nexo",
"NEXO_BRAIN_AUTO_UPDATE": "true"
}
}
}
}Prompts to try
Example prompts that leverage NEXO's memory, workflow, and decision tools.
- "Save a lesson learned: always check for null before accessing nested object properties"
- "Open a new workflow for the authentication refactoring task and checkpoint each step"
- "Recall everything you remember about the database migration we did last week"
- "Check if this action is safe before proceeding using the metacognitive guard"
- "What have I been working on in the last 7 days?"Troubleshooting Nexo
NEXO MCP server fails to start after install
Run 'nexo doctor --tier deep' to diagnose the issue. Common causes are Node.js version below 18 or a corrupted ~/.nexo directory. Delete ~/.nexo and reinstall with 'npm install -g nexo-brain' if needed.
Memory recall returns empty results
NEXO needs at least one session of tool usage to build its memory store. Ensure the AI agent is calling nexo_learning_add or nexo_memory_recall via MCP (check with NEXO_INTERACTIVE=1). The semantic reasoner can be verified with NEXO_SEMANTIC_REASONER=1.
Different AI clients are not sharing the same NEXO memory
All clients must point to the same NEXO_HOME directory (default: ~/.nexo). Verify each client's MCP config has NEXO_HOME set to the same absolute path, and that only one nexo mcp process runs at a time to avoid lock conflicts.
Frequently Asked Questions about Nexo
What is Nexo?
Nexo is a Model Context Protocol (MCP) server that nexo brain — shared brain for ai agents. persistent memory, semantic rag, natural forgetting, metacognitive guard, trust scoring, 150+ mcp tools. works with claude code, codex, claude desktop & any mcp client. 100% local, open source, free. It connects AI assistants to external tools and data sources through a standardized interface.
How do I install Nexo?
Follow the installation instructions on the Nexo GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with Nexo?
Nexo works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is Nexo free to use?
Yes, Nexo is open source and available under the NOASSERTION license. You can use it freely in both personal and commercial projects.
Nexo Alternatives — Similar Knowledge & Memory Servers
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Quick Config Preview
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