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Using Pencil with ChatGPT

Pencil exposes its full underwriting model to ChatGPT over MCP. Connect once and ChatGPT can read your deals, run pricing, and build models with you in conversation. Every change lands in the Pencil app, where you can verify and edit every number.

Connect

  1. 1

    In ChatGPT, open Settings → Apps and find Pencil in the directory. Developers can instead add https://pencil.deals/api/mcp directly as a custom connector.

  2. 2

    Click Connect. You’ll land on a Pencil consent page.

  3. 3

    Sign in with your Pencil account and approve access.

  4. 4

    Start a new conversation and ask about a deal. ChatGPT picks Pencil up automatically when a prompt calls for underwriting.

That’s it. ChatGPT now operates as you, inside your firm’s workspace only. Access uses OAuth 2.1, so there are no API keys to manage, and you can disconnect it anytime from your ChatGPT settings.

What ChatGPT can do

Read

  • List every deal in your pipeline
  • Pull a deal's model summary: NOI, IRR, equity multiple, DSCR, cap rates
  • Run the pricing sensitivity matrix across exit caps and prices
  • Fetch live benchmark rates: SOFR, Treasuries, and swaps

Write

  • Create deals across multifamily, retail, industrial, and office
  • Import rent rolls and T-12 operating statements extracted in the conversation
  • Update model assumptions, from purchase price to per-line expense growth
  • Size and modify financing at current rates
  • Set unit-type rents and designations, add commercial leases
  • Build renovation programs and record tax and valuation data

ChatGPT never touches the model engine directly. Every tool call goes through the same API the Pencil app uses, so the numbers ChatGPT produces are the numbers you see on screen. No black box, no hidden cells.

Things to try

  • “List my deals in Pencil and give me the returns summary on Willow Tree.”
  • “Here's the rent roll and T-12 for a deal I'm screening. Create it in Pencil and import both.”
  • “What does the deal price to at a 5.25% exit cap? Show me the sensitivity.”
  • “Check current rates and size a 65% LTV loan at SOFR plus 250, 5-year term, full-term IO.”
  • “Set Year 1 rent growth to 4% and tell me what it does to the levered IRR.”

Requirements

A Pencil account on any plan, including the 14-day free trial. Solo and Team plans include the connector at no extra cost.

Support

Questions or issues: support@pencil.deals.

Underwrite the next deal without leaving the conversation.

Free for 14 days. No card required.

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