MCP proxy

The MCP proxy sits between the agent client and the real MCP server. The client connects to AvertGate; AvertGate inspects every tools/call and forwards it upstream.

Single upstream

UPSTREAM_COMMAND="npx" \
UPSTREAM_ARGS="-y @modelcontextprotocol/server-filesystem /data" \
npx @avertgate/cli start

Multiple upstreams

UPSTREAM_SERVERS accepts a JSON array, a standard mcpServers dictionary, or a path to a JSON file:

UPSTREAM_SERVERS='{
  "filesystem": { "command": "npx", "args": ["-y", "@modelcontextprotocol/server-filesystem", "/data"] },
  "github":     { "command": "npx", "args": ["-y", "@modelcontextprotocol/server-github"] }
}'

If tool names collide, the second is namespaced as server__tool and referred to by that name in the policy.

Client configuration

In your MCP client define AvertGate as the command instead of the real server:

{
  "mcpServers": {
    "governed": {
      "command": "npx",
      "args": ["@avertgate/cli", "start"],
      "env": { "UPSTREAM_COMMAND": "npx", "UPSTREAM_ARGS": "-y @modelcontextprotocol/server-filesystem /data" }
    }
  }
}

What is inspected?

• tools/call: the full request/response loop.
• resources: the policy's resources rules (uri_pattern).