MCP — the protocol layer

What is MCP?

MCP stands for Model Context Protocol. It is an open, vendor-neutral protocol published by Anthropic in early 2025. Its goal: let LLMs (Claude, ChatGPT, others) talk to tools such as editors, databases, or browser automations in a uniform, well-specified language — instead of writing a custom integration each time.

ForgeIEC implements the server side of MCP — ForgeIEC Studio is an MCP server. Any MCP-compatible client can connect — the most important options:

The built-in chat tab in ForgeIEC Studio itself (default, no setup)
Anthropic Claude Desktop (Mac, Windows, Linux) — ~/Library/Application Support/Claude/claude_desktop_config.json or the equivalent under ~/.config/Claude/; enter URL + bearer token from ForgeIEC Studio there
VS Code with an MCP extension (e.g. Anthropic’s “MCP”) — register the ForgeIEC MCP server in the extension settings as an external MCP endpoint; then you can call ForgeIEC tools from VS Code chat sessions
Claude Code (CLI) — claude mcp add forgeiec https://forgeiec-ws.local:7531 --token <bearer>
ChatGPT (OpenAI) with MCP connector
Custom clients you write yourself (see next section)
mcp-inspector (the official debug tool, npm)

In all cases you need two pieces from ForgeIEC Studio: the server URL (https://<hostname>:7531) and the bearer token from Preferences → AI → Profile → Bearer Token. With those, your external client can execute exactly the same MCP tools as the built-in chat tab.

Who is this section for?

Depending on your role, two entry points:

For application engineers

If you want to call the MCP server of ForgeIEC Studio from your own scripts or tools. Topics:

How the call sequence works (lifecycle)
Authentication via bearer token or client certificate
Reading the tool list
Examples with curl
Handling confirmation prompts
Plug-in API status

For IT + operations

If you deploy, monitor, or integrate ForgeIEC into an existing IT landscape. Topics:

Network: ports, firewall rules, bind address
Certificates: server cert, trust store, renewal
Identities + tokens: bearer per profile
Log files: location, format, rotation
Backup: what to save, what is regeneratable
Monitoring: server_info as a health check for your monitoring
Troubleshooting: common problems + recipes

Architecture picture

flowchart TB
    Client[LLM client
Claude / GPT / Custom]
    Studio["ForgeIEC Studio (MCP server)
• Tools (≈80)
• Confirmation State Machine
• Audit log
• Trust store"]
    anvild[anvild
PLC runtime]
    daemons[bellowsd / tongs-*
HMI + fieldbus]

    Client <-->|HTTP+SSE / JSON-RPC| Studio
    Studio -->|gRPC| anvild
    anvild -->|iceoryx2 SHM| daemons

The MCP server is embedded in the ForgeIEC Studio process — it shares memory and lifecycle with the running project. Tool calls are therefore very fast (no RPC hop), and the client always sees the current in-memory state, not a stale file mirror.

Spec references

For deeper details:

MCP protocol (official): https://modelcontextprotocol.io
MCP inspector (debug tool, npm): https://github.com/modelcontextprotocol/inspector
ForgeIEC’s own MCP spec: in the source tree at documentation/architecture/mcp-platform-v1.md — RFC-2119 normative, approx. 2300 LOC, covers all security and federation decisions