Buildern MCP Server

npx add-mcp 'https://cotlet.dev/mcp/v1/buildern'

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Buildern API and MCP server: Let your AI agent price, schedule and log the job.

Buildern publishes API documentation at api.buildern.com/v1/docs and directs API access through its contact flow. No Buildern MCP server and no official ChatGPT or Claude connector was verified.

Buildern documents a gated API and no Buildern MCP server (checked 13 Nov 2026). Cotlet runs a hosted Buildern MCP server with 21 tools that ChatGPT and Claude use in your own contractor account. Estimates, invoices and anything that reaches a client or a sub wait for your OK.

• Free 7-day trial, no card
• Unofficial, not affiliated with Buildern
• Page: https://cotlet.dev/integrations/buildern-api-mcp-server

What can your AI agent do in Buildern?

• Turn a takeoff into an estimate
• Draft the client proposal
• Move a schedule date and assign to-dos
• Check budgets against bills and orders
• Prepare the next client invoice
• Write today's site diary

Does Buildern have an MCP server or an API?

• The Buildern API docs are public at api.buildern.com/v1/docs; access goes through buildern.com/contact-us.
• Buildern AI is the vendor's own assistant, described on its product page and in its Help Center.
• Buildern documents its own QuickBooks Online and Xero integrations for accounting.

What you need	Buildern API	By hand	Cotlet
Ask ChatGPT or Claude to do the work	No MCP server verified	Copy and paste	Hosted MCP server
Start today with your own login	Request access first	Your login	Your login, once
Estimates, schedules, bills and invoices	Endpoints not verified	One screen at a time	21 tools, writes after your OK
Run from n8n or a script	After access, your own code	Manual only	REST, same key

Checked 13 Nov 2026. Sources: Buildern API documentation, Buildern contact page, Buildern AI, Buildern Help Center, Help: Buildern AI, Help: Quickbooks Online Integration, Help: Xero Integration, Help: Users, Roles, Permissions, Help: Projects, Help: Dashboards, Help: Takeoff, Help: Estimates, Help: Cost Codes, Help: Proposals, Help: Schedule, Help: Bid Requests / Request for Quote, Help: Selections and Allowances, Help: Purchase Orders, Help: Bills, Help: Budget Tab, Help: Change Orders / Variations, Help: Client Invoices, Help: To-Dos, Help: Daily Logs / Site diary, Help: Timesheets, Help: Files, Help: Clients, Help: Subcontractors & Vendors, Help: Templates

How does the Buildern MCP server work?

1. Sign in to Buildern. Once, in a browser we host for you.
2. Connect your AI agent. One address in its settings.
3. Hand it the paperwork. Price a takeoff, then approve the estimate.

Your agent works in your own signed-in Cloud Browser. Writes, and anything that reaches a client or a sub, wait for your OK.

How to connect Buildern to your AI agent

1. Sign in to Buildern in a Cloud Browser. Open app.buildern.com in your Cotlet Cloud Browser and sign in with your own Buildern user.
2. Add the Cotlet address. Enter https://cotlet.dev/mcp/v1 as the MCP server or connector URL in your agent.
3. Let the agent in. Chat apps open a Cotlet sign-in page. Editors, n8n and scripts send an API key made in the console.

Buildern sits on the shared address https://cotlet.dev/mcp/v1 with every other app you enable, so one connector covers them all. Turned Buildern on after connecting? Refresh the connector and the 21 Buildern tools appear.

ChatGPT:

Settings > Apps & Connectors > Create
MCP server URL: https://cotlet.dev/mcp/v1/connect
Authentication: OAuth

Claude:

Settings > Connectors > Add custom connector
URL: https://cotlet.dev/mcp/v1/connect

Claude Code:
claude mcp add --transport http cotlet \
  https://cotlet.dev/mcp/v1 \
  --header "Authorization: Bearer $COTLET_API_KEY"

Cursor:

// ~/.cursor/mcp.json
{
  "mcpServers": {
    "cotlet": {
      "url": "https://cotlet.dev/mcp/v1",
      "headers": { "Authorization": "Bearer ${env:COTLET_API_KEY}" }
    }
  }
}

Codex:

# ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"

n8n:

MCP Client Tool (inside an AI Agent)
Transport: HTTP Streamable
URL: https://cotlet.dev/mcp/v1
Auth: Bearer, <your key>
Tool: buildern_read

All 21 Buildern MCP tools

One tool per workflow in the Buildern Help Center. Most take an action: list and get only read, the other actions write and ask first.

Projects and dashboards

Start here: most other tools take a project name. Dashboards and the Budget tab are read only.

• Create and update projects (manage_projects, write, asks first): List, open, create or update a project in Buildern.
• View dashboards (view_dashboards, read): Read a Buildern dashboard, for the whole company or one project.
• View project budget (manage_budget_tab, read): Read the Budget tab of one Buildern project, line by line.

Takeoffs, estimates and proposals

From measured quantities to the document your client reads. The agent enters quantities you give it; it does not measure drawings.

• Create quantity takeoff (perform_takeoff, write, asks first): List or read a project's takeoffs, or record a new quantity takeoff.
• Create estimates (create_estimates, write, asks first): List or read a project's estimates, or create one from lines or a takeoff.
• Set cost codes (manage_cost_codes, write, asks first): List your Buildern cost codes, add one or rename one.
• Create proposals (create_proposals, write, asks first): List or read a project's proposals, or create one for the client.
• Create templates (manage_templates, write, asks first): List your Buildern templates or save a new one.

Schedule and site work

Dates, to-dos, the daily log or site diary, crew hours and project files.

• Schedule project work (manage_schedule, write, asks first): Read a project's schedule, add a task or move its dates.
• Track to-dos (manage_to_dos, write, asks first): List a project's to-dos, add one, reassign it or mark it done.
• Add daily logs (record_daily_logs_site_diary, write, asks first): Read a project's daily logs, or add today's site diary entry.
• Track timesheets (track_timesheets, write, asks first): Read timesheets, or enter hours for a team member on a project.
• Upload files (manage_files, write, asks first): List a project's files or upload one to it.

Buying: bids, orders and bills

Requests for quote reach subcontractors and vendors outside your company; orders and bills are money. Each write waits for your OK.

• Request bids (manage_bid_requests_request_for_quote, write, asks first): List bid requests or send a request for quote to subcontractors and vendors.
• Create purchase orders (manage_purchase_orders, write, asks first): List or read a project's purchase orders, or create one for a vendor.
• Add bills (manage_bills, write, asks first): List a project's bills or add a vendor or subcontractor bill.

Client money: selections, change orders and invoices

Everything here changes what your client pays. Preparing an invoice and sending it are separate calls.

• Set selections and allowances (manage_selections_and_allowances, write, asks first): Read or set a project's selections and the allowance for each.
• Add change orders (manage_change_orders_variations, write, asks first): List a project's change orders or variations, or add one.
• Send client invoices (manage_client_invoices, write, asks first): List or read client invoices, prepare one or send it to the client.

Clients, subcontractors and vendors

The people the other records point at. Add a sub here before sending them a bid request.

• Add clients (manage_clients, write, asks first): List or read your Buildern clients, or add a new one.
• Add subcontractors and vendors (manage_subcontractors_vendors, write, asks first): List your subcontractors and vendors, or add one.

Inputs, REST path and example response of every tool: https://cotlet.dev/integrations/buildern-api-mcp-server#tools

Who can see my Buildern session, and how do I revoke it?

• What we store. Your signed-in Buildern browser profile, AES-256-GCM encrypted, in Finland. Never your password.
• What your agent gets. The 21 Buildern tools. The session cookie stays in the Cloud Browser.
• What the session sees. The projects, estimates and money records your Buildern user and role can open, and nothing more.
• What no tool touches. Buildern users, roles and permissions, account settings and the QuickBooks Online and Xero connections.
• If Buildern signs you out. You sign in again yourself, in the same Cloud Browser.
• How to cut access. Disable Buildern for agents, reset the browser, or change your Buildern password.

You type your Buildern password yourself; the agent only uses the session that sign-in leaves behind. Our site scores A+ on Qualys SSL Labs, securityheaders.com and Mozilla Observatory (live results).

What happens when Buildern changes?

Cotlet watches the apps it serves and updates the Buildern server when Buildern changes its screens, so your agent keeps working without a code change on your side.

New Buildern features become available to the agent. It still sees only what your own Buildern user and role can see, so a login with fewer permissions gives the agent fewer records.

If Buildern signs you out, one click in the Cotlet console reopens the Cloud Browser so you can sign in again.

Approvals, undo and mistakes

1. Read the takeoff. perform_takeoff returns the quantities.
2. Check cost codes. manage_cost_codes lists the codes you use.
3. Show you the estimate. Lines and total, before anything is saved.
4. Save after your OK. create_estimates writes it, then the proposal.

Action	How to put it right
Project details, schedule dates, to-dos	Call manage_projects, manage_schedule or manage_to_dos again with the earlier values
Cost code names	Rename the code back with manage_cost_codes
Bid request	Already with your subs and vendors: follow up with them directly
Client invoice, once sent	Already with your client: talk to them before you change it

All 19 write tools ask first: by default you confirm each call, and you can switch that off per tool. The 2 read tools, dashboards and the Budget tab, run at once.

MCP call:

{
  "name": "create_estimates",
  "arguments": {
    "action": "create",
    "project": "Oak Lane kitchen remodel",
    "name": "Kitchen remodel, base scope",
    "lines": [
      {
        "description": "Base cabinets, supply and install",
        "cost_code": "CAB",
        "quantity": 14,
        "unit": "lf",
        "unit_cost": 310
      },
      {
        "description": "Quartz countertop",
        "cost_code": "CTP",
        "quantity": 42,
        "unit": "sq ft",
        "unit_cost": 85
      },
      {
        "description": "Backsplash tile",
        "cost_code": "TIL",
        "quantity": 30,
        "unit": "sq ft",
        "unit_cost": 24
      }
    ]
  }
}

REST:

curl -X POST https://cotlet.dev/api/v1/buildern/estimates \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"action":"create","project":"Oak Lane kitchen remodel","name":"Kitchen remodel, base scope","lines":[{"description":"Base cabinets, supply and install","cost_code":"CAB","quantity":14,"unit":"lf","unit_cost":310},{"description":"Quartz countertop","cost_code":"CTP","quantity":42,"unit":"sq ft","unit_cost":85},{"description":"Backsplash tile","cost_code":"TIL","quantity":30,"unit":"sq ft","unit_cost":24}]}'

Response:

{
  "project": "Oak Lane kitchen remodel",
  "estimate": "Kitchen remodel, base scope",
  "lines": 3,
  "total": 8630,
  "saved": true
}

The example prices 14 lf of base cabinets at $310, 42 sq ft of quartz at $85 and 30 sq ft of tile at $24: $8,630 in all. A cron job or n8n flow can make the same call over REST at /api/v1/buildern with the same key and price, in JSON. Failed calls are free.

How much does the Buildern MCP server cost?

About $29 a month for a small contractor running three projects, 5,000 credits. Your Buildern plan stays as it is.

Job	Calls	Credits
Morning dashboard and to-do check	2 × 20	400
Daily log on three projects	3 × 20	600
Schedule moves	2 × 20	400
Supplier bills and purchase orders	1 × 90	900
Crew hours into timesheets	15 × 4	600
Takeoff, estimate and proposal for a new job	3 × 10	300
Friday budget review, three projects	3 × 4	120
Change orders and client invoices	1 × 18	180
Cloud Browser, 30 days		1,500
Total	350 calls	5,000

The smallest pack, 5,000 credits for $29, covers this month. A busier office with more projects uses more calls.

• Free 7-day trial, no card
• 10 credits per successful call, MCP or REST
• 50 credits a day for the Cloud Browser
• Your Buildern plan and role apply as they are

Credit packs are one-time purchases, not a subscription. The month above is an example built from our own assumptions, not measured customer usage.

Buildern MCP server: other ways to connect

Option	What it does	Where it stops
Buildern API	Documented at api.buildern.com/v1/docs for your own code.	Access through Buildern's contact flow; you write, host and fix the client.
Buildern AI	Buildern's own assistant, inside Buildern.	No official ChatGPT or Claude connector was verified.
QuickBooks Online and Xero integrations	Buildern's own links to those accounting tools.	Set up in Buildern for accounting, not a route for an AI agent.
By hand	Open each project in Buildern and click through.	One screen at a time, only while you are at the desk.

If you get access to the Buildern API and it covers your job, use it: it is the vendor's own route. Cotlet fits when you want ChatGPT, Claude or a script working in Buildern today, from your own login, with nothing to host.

Who runs Cotlet

Cotlet is run by Take Group sp. z o.o., a software company registered in Poland, EU (VAT PL6342984273) and in business since 2019. Its founders are Bart Krawczyk (Co-founder, CTO) and Jake Slugocki (Co-founder, SEO, sales and marketing). Write to contact@cotlet.dev with questions about the Buildern tools.

Buildern MCP server: questions

How do I get access?

Sign up free at https://cotlet.dev/signup?app=buildern, turn on Buildern under Integrations in the console and sign in at https://app.buildern.com/ in your Cloud Browser. Then connect your AI agent and ask it to work on a project. The trial needs no card.

Does Buildern have an API?

Buildern publishes API documentation at api.buildern.com/v1/docs and directs API access through its contact flow (checked 13 Nov 2026). No Buildern MCP server and no official ChatGPT or Claude connector was verified; Buildern AI is the vendor's own assistant. Cotlet does not use that API: it works in your own signed-in Buildern account.

How is this different from Buildern AI?

Buildern AI is Buildern's own assistant, documented in its Help Center. Cotlet is separate: it lets ChatGPT, Claude or a script you choose work in your Buildern account with the same tools over MCP or REST.

Does Cotlet set up the QuickBooks Online or Xero connection?

No. Buildern documents its own QuickBooks Online and Xero integrations in its Help Center; you set those up in Buildern. No Cotlet tool changes them, or your users, roles, permissions and settings.

Which Buildern user should I sign in with?

Use the user whose work the agent should do. The agent sees only what that user and its role can see in Buildern, so a user without access to client invoices gives the agent no access to them either.

Is the MCP server different from the REST API?

Only in how it is called. Both carry the same 21 tools, inputs, answers, API key and price. Agents use MCP; scripts and n8n HTTP steps use REST.

Is Cotlet affiliated with Buildern?

No. Cotlet is independent and not affiliated with Buildern.

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