tool-filter-mcp
Verified Safeby respawn-app
Overview
A proxy server for Model Context Protocol (MCP) that filters available tools from upstream MCP servers based on a regex-based deny list to optimize context for AI agents.
Installation
npx @respawn-app/tool-filter-mcp --upstream http://localhost:3000/sse --deny ".*_file$"Environment Variables
- API_KEY
- AUTH_TOKEN
- CUSTOM_VALUE
- DEBUG
- MY_API_KEY
Security Notes
The project uses `safe-regex2` to validate deny patterns, mitigating ReDoS vulnerabilities. It handles sensitive information by supporting environment variable expansion for authentication headers, preventing hardcoded secrets. In stdio mode, it spawns child processes for upstream servers, which is an inherent risk if the executed command is not carefully controlled by the deployer, though the tool itself does not introduce arbitrary user command execution.
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