native-mcp

Add an entry under the mcp_servers key in ~/.hermes/config.yaml with either a command and args for stdio servers or a url for HTTP servers. Restart the agent and its tools are discovered and registered automatically with an mcp_{server}_{tool} prefix.

Set the command field to npx or uvx and pass the package name in args, for example command: npx with args: ["-y", "@modelcontextprotocol/server-filesystem", "/path"]. Node.js is required for npx servers and uv for uvx servers.

Yes, HTTP and StreamableHTTP transports are supported by setting a url instead of a command, with optional headers for authentication. Your installed mcp package must include mcp.client.streamable_http support.

Stdio subprocesses receive only a filtered baseline of safe variables like PATH and HOME, not your full shell environment. Credentials must be explicitly passed via the env config key, and credential patterns are redacted from error messages.

Check that servers are listed under the mcp_servers key with correct YAML indentation and that the mcp Python package is installed. Tools are prefixed with mcp_{server}_{tool}, so search for that naming pattern in startup logs.

The client automatically reconnects with exponential backoff up to 5 retries, capped at 60 seconds between attempts. If the server remains unreachable after all retries, that server is abandoned while others continue normally.