In-app assistant: the ✦ Assistant button in the builder opens a chat that reads your current design, modifies it, solves it, and runs annual simulations — conversationally, in your language. Store your own Anthropic API key (assistant ⚙ → key settings) for unlimited chat billed to your Anthropic account, or use the platform key, metered through simulation tokens.
MCP connector: HVAC Builder is an MCP server. In Claude, add a custom connector with this URL — nothing to paste, sign in when it asks:
https://hvacbuilder.app/api/mcp
The connector registers itself, sends you here to approve it, and gets an access token scoped to your account. It works exactly as you do, with your tier's entitlements — and cannot approve further connections, change your plan, or reach admin tools. Disconnect it any time under avatar menu → Connections & API keys.
What it can reach: your saved systems, buildings and runs, the component and weather catalogs, and — if you are a supplier — your listings and RFQ leads. Tools that only read or compute are marked read-only, so a client can run them without asking each time; the three that write to your account (save_system, simulate_annual, import_catalog_items) only ever create, never edit or delete. See the privacy policy for what is stored and for how long.
Without OAuth — scripts, CI, or a client that only takes a token — create an API key (same menu) and send it as Authorization: Bearer hvb_…, or as ?key=hvb_… for connector UIs that only take a URL. Keys work on the whole REST API too.
Tools: list_component_kinds (schema + worked example), solve_system, simulate_annual, save_system, list_weather_datasets, list_supplier_presets — plus vendor tools below. Prompt requirements in plain language; the result lands in your account, ready to open in the builder.