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Works with the AI Agents you already use
Claude Code
Cursor
Codex CLI
Muse
Dots+22 moreClaude CodeCursorCodex CLIMuseDots
OpenClaw
Manus
Grok
Grok Bot+18 agentsmcp-bastion: Self-Healing, Secure MCP Server Proxy
Keeps your MCP servers connected and blocks tool poisoning and rug-pull attacks, with no changes to your servers.
Free
mcp-bastion: Self-Healing, Secure MCP Server Proxy
Example session with this skill installed
My filesystem MCP server keeps dropping in the middle of long sessions, and then the agent says "No such tool available". Put mcp-bastion in front of it so it reconnects on its own.
- Read your context and instructions
- Compiled the mcp-bastion
I'll put mcp-bastion between your client and the filesystem server. Your server runs unchanged, and you can undo this by restoring your old config.
1. Move the server into bastion.config.json
I copied your existing filesystem entry as it was:
{
"servers": {
"filesystem": {
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/you/projects"]
}
},
"reconnect": { "auto": true },
"healthCheck": { "enabled": true }
}
2. Point your client at Bastion
Your .mcp.json now has one entry. I used an absolute path, because clients often start servers from a different folder:
{
"mcpServers": {
"bastion": {
"command": "npx",
"args": ["-y", "mcp-bastion", "--config", "/Users/you/bastion.config.json"]
}
}
}
3. Check it's working
After the restart I called bastion__status:
{
"servers": [
{
"name": "filesystem",
"state": "connected",
"connected": true,
"transport": "stdio",
"authenticated": null,
"tools": 14,
"lastError": null
}
]
}
| What | Result |
|---|---|
| Filesystem server | Connected, 14 tools |
| Tool names | Now prefixed with the server name, e.g. filesystem__read_text_file |
| Bastion control tools | bastion__status, bastion__reconnect, bastion__security, bastion__compliance |
| Security | On, balanced profile (blocks rug pulls and injection, warns on heuristics) |
| Test read | filesystem__read_text_file returned the file through Bastion |
What changes for you: if the server drops again, Bastion reconnects it automatically. If a tool call fails mid-session, I'll check bastion__status, call bastion__reconnect once, and retry. If it still fails, I'll show you the server's last error instead of guessing.
Connects securely to your tools. The creator never sees your data.
About this skill
The problem
When an MCP server crashes or disconnects mid-session, your agent just sees "No such tool available". It can't tell a dropped server from a tool that never existed, and it can't reconnect. You have to restart things by hand.
Third-party MCP servers bring a second risk. A server can look harmless when you install it, then change a tool's definition later, or hide instructions in a tool description that steer your agent.
What this skill does
This skill teaches your agent to set up and use mcp-bastion, an open-source proxy that sits between your AI client and your MCP servers.
- Self-healing connections. Bastion health-checks every server and reconnects automatically with backoff. Your agent gets
bastion__statusandbastion__reconnectso it can find and fix a dropped server itself. - Runtime security, on by default. Bastion pins every tool definition and blocks a tool that changes after it was pinned (a "rug pull"). It also flags poisoned tool descriptions, injection in tool arguments, tool shadowing across servers and leaked secrets in results.
- Audit trail (opt-in). Bastion records a structured event for every tool call, mapped to the NIST AI RMF and the OWASP LLM Top 10, and sends it to a file, a webhook or OpenTelemetry.
- No changes to your servers. You move your existing server entries into one config file. To undo, restore your old client config.
The skill also tells the agent how to behave: reconnect once and report if it still fails, never work around a security block, and leave clearing a blocked tool to you.
Works with
Claude Code, Cursor, Claude Desktop, Cline, Windsurf and any MCP client. The skill includes the config file location for each one.
Requirements
- Node.js 20 or newer
- At least one MCP server you already use
Free and open source
mcp-bastion is free under the Apache-2.0 licence. Its security coverage is measured on the open mcp-defense-bench benchmark.
Created and maintained by Gowthaman Arumugam.
How to use
Skills on Agensi run inside your AI agent. Copy the prompt, paste it into your agent, and it connects to Agensi and installs this skill for you. If a payment is needed, your agent shows it to you first.
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Requires
Node.js