MCP Integration for OpenConstructionERP

Why MCP

MCP (Model Context Protocol) is the 2026 standard for giving AI assistants tools. Wrapping OpenConstructionERP's REST API in an MCP server turns the assistant from a chat partner into an operator: it can load a cost base, search items, build a BOQ and read validation results itself.

What to expose (start with these)

MCP tool	Underlying API	Notes
list_cost_bases	GET /api/v1/costs/base-catalog	families, variants, positions, loaded badge
load_cost_base	POST /api/v1/costs/load-cwicr/{db_id}	idempotent, returns imported/skipped
search_cost_items	GET /api/v1/costs/?region=...&q=...	SQL path, works without Qdrant
get_cost_item	GET /api/v1/costs/{id}	full components[] + classification
category_tree	GET /api/v1/costs/category-tree/?region=...	browsing
suggest_for_element	POST /api/v1/costs/suggest-for-element	BIM element → cost ranking
create_boq / validate_boq	POST /api/v1/boqs, /boqs/{id}/validate/	estimating
import_catalog	POST /api/v1/catalog/import/{region}	resource catalog

Reference implementation (TypeScript, fast)

// mcp-server: FastMCP wrapper around the ERP's FastAPI backend
import { FastMCP } from "fastmcp";

const ERP = process.env.OPENESTIMATE_URL ?? "http://localhost:8000";
const server = new FastMCP({ name: "openconstructionerp" });

server.addTool({
  name: "load_cost_base",
  description: "Load a CWICR cost base (e.g. TR_NATIONAL, ZH_CHINA) into the ERP.",
  parameters: { db_id: { type: "string", required: true } },
  execute: async ({ db_id }) => {
    const r = await fetch(`${ERP}/api/v1/costs/load-cwicr/${db_id}`, {
      method: "POST",
      headers: { Authorization: `Bearer ${process.env.ERP_TOKEN}` },
    });
    return await r.json();
  },
});

server.addTool({
  name: "search_cost_items",
  description: "Search cost items in a region by keyword.",
  parameters: { region: { type: "string" }, q: { type: "string" } },
  execute: async ({ region, q }) => {
    const r = await fetch(`${ERP}/api/v1/costs/?region=${region}&q=${encodeURIComponent(q)}&limit=20`,
      { headers: { Authorization: `Bearer ${process.env.ERP_TOKEN}` } });
    return await r.json();
  },
});

server.start({ transportType: "stdio" });

Auth & safety

• Reuse the ERP's JWT (register a service account; bootstrap admin only for setup).
• MCP tools must be idempotent and read-mostly: load_cost_base returns already_loaded on repeat.
• Never expose raw credentials in tool descriptions; use env vars (ERP_TOKEN).
• Rate-limit write tools; the ERP already enforces api_rate_limit (200/min default).

Best practices

1. Start read-only (browse/search), add writes (BOQ create, link) after testing.
2. Wrap long operations (BIM conversion) in a progress-tool pattern instead of blocking.
3. Log every assistant action server-side (the platform's usage ledger pattern).
4. Publish the MCP server to the assistant marketplace (Claude Code registry, Antigravity, OpenCode).