Reticle sits between the MCP client and MCP server and inspects JSON-RPC traffic.

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│   MCP Client    │────▶│   mcp-reticle   │────▶│   MCP Server    │
│ (Claude, Cline) │◀────│      (CLI)      │◀────│   (your tool)   │
└─────────────────┘     └────────┬────────┘     └─────────────────┘
                                 │ Telemetry
                                 ▼
                        ┌─────────────────┐
                        │   Reticle UI    │
                        │ (Tauri + React) │
                        └─────────────────┘

1. Client sends JSON-RPC requests/notifications to the server
2. Reticle forwards traffic transparently (client ↔ Reticle ↔ server)
3. Reticle parses messages and emits telemetry (message, timing, direction, correlation ids)
4. The UI renders message streams, correlations, latency, and token estimates

• stdio: mcp-reticle run wraps a process and intercepts stdin/stdout
• HTTP-based: mcp-reticle proxy reverse-proxies upstream servers and intercepts traffic
• headless hub: mcp-reticle daemon aggregates telemetry without the UI

See: CLI