Hermes-style MCP config is a good target for OpenAPI generation because it is mostly wiring: command, args, env, transport, and a tool filter.
The hard part is not creating YAML. The hard part is deciding what tools can be enabled safely.
What Sourced emits
For Hermes, the Sourced-generated pack includes:
- a local stdio MCP server config
- an HTTP MCP config when a hosted URL is available
- environment variables for upstream API auth
- a default include list of safe read-only tools
- exclusions for destructive tools
- a readiness report explaining any blockers
That output is copyable and explainable. A maintainer can open the generated files and see why each tool was included or excluded.
Local first, remote later
If there is no hosted MCP endpoint yet, generate a local config:
mcp_servers:
your-api:
command: "node"
args:
- "/absolute/path/to/your-api-mcp/dist/index.js"
Once the HTTP server is deployed behind HTTPS, the config can move to a remote transport with the same tool filter.
Keep the include list narrow
Large OpenAPI specs produce large tool lists. Large tool lists make agent behavior harder to predict.
Start with:
- list endpoints
- retrieve endpoints
- search endpoints
- validation endpoints
Leave these out by default:
- billing reads
- user exports
- API key reads
- create/update actions
- delete/cancel/refund/revoke actions
The generated Hermes config preserves that distinction through include and, where useful, exclude.
Make review cheap
The best generated config includes context right next to it:
- total tools
- default-enabled tools
- sensitive reads
- write tools
- destructive tools
- missing operation IDs
- vague descriptions
That lets a team approve the config without reverse-engineering the generator.
The Sourced path
Sourced's MCP generator emits connector.hermes.config.yml as part of the Agent Interface Pack. It uses the same OpenAPI parse, safety classification, and default allowlist as the ChatGPT, Grok, Claude, Cursor, and VS Code outputs.
That is the point: one OpenAPI input, one safety review, multiple install targets.