Roll Out MCP with a Least-Privilege Tool Surface
MCP is an adapter layer: Hermes remains the agent, while an MCP server contributes tools that Hermes discovers at startup or reload time. The practical goal is not to connect every available system. It is to expose the smallest useful capability set for one defined workflow. The official guide recommends MCP when an existing server offers a clean integration or fine-grained exposure control, and advises against an unfiltered server with a large destructive surface.[1]
Start with one bounded use case
Choose a low-risk first job, such as reading one project directory, inspecting one repository, or querying documentation. Scope a filesystem server to one project directory rather than an entire home directory. Point a git server at one repository. For an internal API, begin with read-heavy operations. If a built-in Hermes tool already handles the task cleanly, adding MCP may create complexity without useful isolation.[1]
Prefer allowlists over cleanup
For financial, customer-facing, or destructive systems, use tools.include as the default policy and list only the operations required by the workflow. An exclude list can remove known hazards, but it leaves newly added or overlooked actions visible; a tight include list fails closed. Disable server-provided prompt and resource wrappers with prompts: false and resources: false when the workflow does not need them.[1]
Expand in small increments. If the first workflow only needs issue listing and code search, do not expose update, delete, refund, publish, or administrative actions. Add one capability only when a real use case requires it, then reload MCP and recheck the registered tools. Credentials should remain in the configured environment or authentication headers—not in prompts, wiki pages, logs, or example values.
Distinguish connection from authorization
A server connecting successfully only proves transport and authentication worked. It does not prove the tool surface is appropriate. Likewise, a work-record or planning server may record decisions without authorizing Hermes to merge, deploy, publish, or start unrelated runtimes. Keep business approval boundaries outside the integration and document who can authorize state-changing operations.[1]
For package-launched servers, consider pinning a version when reproducible tool schemas matter. A server update can otherwise alter capabilities even when your Hermes prompt has not changed.
Rollout checklist
- Define one workflow and the minimum operations it actually needs.
- Connect one server with directory, repository, or API scope kept narrow.
- Use
tools.includefor sensitive or state-changing systems. - Disable unused prompt and resource wrappers.
- Reload MCP after policy, authentication, or enablement changes.
- Inspect the registered tool list and run one low-risk functional test.
Common pitfalls
- Rooting a filesystem server at an entire home directory.
- Connecting a large business system before understanding its actions.
- Relying only on an exclude list for a dangerous or evolving server.
- Leaving prompts or resources enabled when the workflow never uses them.
- Assuming a successful connection means least privilege is achieved.
- Expanding write capabilities without a named owner and approval rule.
Verification
Confirm Hermes reports MCP as loaded, then inspect which tools are actually available. Verify that required operations appear and forbidden operations do not. Run a harmless read operation, review logs for connection failures, and test /reload-mcp after a controlled policy change. Recheck the surface whenever server versions, credentials, include lists, or capability toggles change.