# Hermes MCP — Setup & Deployment

Hermes is a multi-account email MCP server for Claude AI.
It supports **Yahoo Mail** (IMAP App Password) and any **custom IMAP/SMTP server**.

---

## Local development

```bash
# 1. Install dependencies
npm install

# 2. Copy and fill in credentials
cp .env.example .env
# edit .env with your email credentials

# 3. Run in dev mode (hot-reload)
npm run dev

# 4. Test health
curl http://localhost:3456/health
# → {"status":"ok","service":"hermes-mcp"}
```

---

## Production deployment (Kubernetes example)

Example deployment using MicroK8s single-node cluster.
SSL is handled by `cert-manager` with a Let's Encrypt certificate.

### Prerequisites on the server
- MicroK8s with addons: `dns`, `ingress`, `registry`, `cert-manager`
- Local registry at `localhost:32000`
- A `ClusterIssuer` named `letsencrypt-prod` already configured

### One-time: create K8s namespace and secret
```bash
microk8s kubectl create namespace hermes-mcp   # if it doesn't exist

microk8s kubectl create secret generic hermes-mcp-env -n hermes-mcp \
  --from-literal=YAHOO_EMAIL=your@yahoo.com \
  --from-literal=YAHOO_APP_PASSWORD=your-app-password \
  --from-literal=CUSTOM_EMAIL=your@domain.com \
  --from-literal=CUSTOM_PASSWORD=your-password \
  --from-literal=CUSTOM_IMAP_HOST=mail.yourdomain.com \
  --from-literal=CUSTOM_IMAP_PORT=993 \
  --from-literal=CUSTOM_SMTP_HOST=mail.yourdomain.com \
  --from-literal=CUSTOM_SMTP_PORT=587 \
  --from-literal=PORT=3456
```

### Build & push image
```bash
# Option 1: Build locally and push to your registry
docker build -t localhost:32000/hermes-mcp:latest .
docker push localhost:32000/hermes-mcp:latest

# Option 2: Copy to server and build there
scp -r src/ package*.json tsconfig.json Dockerfile user@your-server:~/hermes-mcp/
ssh user@your-server "cd ~/hermes-mcp && docker build -t localhost:32000/hermes-mcp:latest . && docker push localhost:32000/hermes-mcp:latest"
```

### Apply K8s manifests
```yaml
# hermes-k8s.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hermes-mcp
  namespace: hermes-mcp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hermes-mcp
  template:
    metadata:
      labels:
        app: hermes-mcp
    spec:
      containers:
        - name: hermes-mcp
          image: localhost:32000/hermes-mcp:latest
          ports:
            - containerPort: 3456
          envFrom:
            - secretRef:
                name: hermes-mcp-env
          readinessProbe:
            httpGet:
              path: /health
              port: 3456
            initialDelaySeconds: 5
            periodSeconds: 10
---
apiVersion: v1
kind: Service
metadata:
  name: hermes-mcp
  namespace: hermes-mcp
spec:
  selector:
    app: hermes-mcp
  ports:
    - port: 3456
      targetPort: 3456
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hermes-ingress
  namespace: hermes-mcp
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/proxy-buffering: "off"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "3600"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "3600"
spec:
  ingressClassName: nginx
  rules:
    - host: hermes.yourdomain.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: hermes-mcp
                port:
                  number: 3456
  tls:
    - hosts:
        - hermes.yourdomain.com
      secretName: hermes-tls
```

Apply the manifests:
```bash
microk8s kubectl apply -f hermes-k8s.yaml
```

### Redeploy after code changes
```bash
# Rebuild and push the image
docker build -t localhost:32000/hermes-mcp:latest .
docker push localhost:32000/hermes-mcp:latest

# Restart the deployment
microk8s kubectl rollout restart deployment/hermes-mcp -n hermes-mcp
microk8s kubectl rollout status deployment/hermes-mcp -n hermes-mcp
```

---

## Useful commands

```bash
# Logs
microk8s kubectl logs -n hermes-mcp -l app=hermes-mcp --tail=100 -f

# Pod status
microk8s kubectl get pods -n hermes-mcp -l app=hermes-mcp

# Update a single env var without rebuild (takes effect on next rollout)
microk8s kubectl set env deployment/hermes-mcp -n hermes-mcp KEY=value
microk8s kubectl rollout restart deployment/hermes-mcp -n hermes-mcp

# Health check
curl https://hermes.yourdomain.com/health
```

---

## Add to Claude.ai

1. Go to **Claude.ai → Settings → Connectors → Add custom connector**
2. Enter URL: `https://hermes.yourdomain.com/mcp` (or your server's URL)
3. Click Connect

### Available tools

| Tool | Description | Key params |
|------|-------------|------------|
| `get_profile` | Get email address for an account | `account` |
| `search_messages` | Search INBOX by keyword/sender/subject | `q`, `maxResults`, `account` |
| `read_message` | Read full message body by UID | `uid`, `account` |
| `list_folders` | List all mailbox folders | `account` |
| `create_draft` | Save a draft to the Drafts folder | `to`, `subject`, `body`, `account` |
| `send_email` | Send an email | `to`, `subject`, `body`, `account` |

`account` is always optional and defaults to `"yahoo"`. Configure your second account in the code if needed.

---

## Known issues & fixes

| Issue | Cause | Fix |
|-------|-------|-----|
| `read_message` timeout | `source: true` downloads full raw RFC822 | Use `bodyParts: ['TEXT']` instead |
| `messageFlagsAdd` deadlock | Called inside `for await` loop while FETCH active | Moved to after the loop |
| Stale session after pod restart | Session ID guard blocked re-initialize | Accept initialize regardless of session ID |
| `EAI_AGAIN` DNS errors | K8s internal DNS resolution issues | Use direct IP instead of hostname |