What is an MCP server, and why construction teams need one

MCP, the Model Context Protocol, is an open standard for connecting AI assistants to the systems where work happens. It was introduced by Anthropic in 2024 and is now supported by Claude, ChatGPT and a growing list of other AI tools. Instead of every AI tool needing custom code for every system, each system offers an MCP server and every AI tool that speaks MCP can use it.

There are three parts:

• The AI assistant (the MCP client), such as Claude or ChatGPT, where people ask questions.
• The MCP server, which describes what can be asked and answers from the underlying system.
• The system itself: a database, an API or files, such as your job-cost ledger.

When someone asks a question, the assistant looks at the tools the server offers, asks it for the data it needs, and writes the answer from what comes back.

• It is spread over many systems. Job cost in one, project management in another, documents somewhere else.
• Some of it is on premise. Systems such as Sage 300 CRE and many Vista installations run on servers inside the company network with no public API.
• Every system names things differently. A “commitment” in one is a “subcontract” or a “PO” in another, and the tables are not documented for outsiders.
• It is sensitive. Payroll, personal records and margins must not be exposed to everyone who can type a question.

Exporting reports into a chat window works once, but the figures are stale the next day, and nobody controls what was shared.

• Read only. It should only ever read. Writing back to accounting systems is a separate decision with separate controls.
• Speak construction. It should understand jobs, cost codes, commitments, change orders and billing, so “over budget on labor” means the same thing whichever system holds the data.
• Reach on-premise systems safely. An agent inside the network should connect outward, so no inbound firewall ports are opened.
• Respect who is asking. Each person should see only the systems, kinds of data and jobs they are allowed to.
• Keep sensitive fields out by default. Payroll and personal data should be refused unless someone deliberately allows them.
• Show where answers came from. Every figure should say which system it came from and how current it is.

Junction is one MCP server for many construction systems. It offers AI assistants a small, fixed set of read-only tools: list the systems connected for your company, describe what each kind of record contains, query records with filters and totals, and page through long results. Queries are built from a signed data model, never from text the assistant writes, and every request is checked against what the person asking is allowed to see. Read more on our security page.

Systems on the early-access list:

• Viewpoint Vista MCP server (construction accounting and erp)
• Trimble Spectrum MCP server (construction accounting and erp)
• Foundation Software MCP server (construction accounting)
• Sage 300 Construction and Real Estate MCP server (construction accounting and erp)
• ComputerEase MCP server (construction accounting)
• CMiC MCP server (construction erp)
• QuickBooks Desktop MCP server (general accounting)
• Autodesk Build MCP server (construction project management)
• e-Builder (Trimble Unity Construct) MCP server (owner-side capital program management)
• Owner Insite MCP server (owner-side project management)

Next in line: Primavera P6, Aconex, BuildingConnected, Primavera Unifier, Textura, Fieldwire, Trimble Connect, Primavera Cloud, SafetyCulture, Accubid, Simpro, Sage 100 Contractor, Ajera, Vantagepoint, Jobpac, Dynamics GP, Sage 200, MYOB, BILL, JD Edwards, COINS, Hyphen BuildPro, HammerTech, ServiceTitan. See all 200 systems and where each stands.

What does MCP stand for?

MCP stands for Model Context Protocol. It is an open standard, introduced by Anthropic in 2024 and now supported by Claude, ChatGPT and other AI tools, for connecting AI assistants to outside systems and data.

What is the difference between an MCP server and an API?

An API is how one program talks to another. An MCP server sits on top of one or more APIs or databases and describes, in a standard way, what an AI assistant can do with them and what the data means. The assistant needs no custom code for each system: it discovers the server's tools and uses them.

Can an MCP server change data in my accounting system?

It depends on the server. Some MCP servers can write. Junction is read-only by design: it only ever reads, builds its queries from a fixed data model, and asks for read-only database logins and API keys as a second safeguard.

Does the AI company see my construction data?

The rows that answer a question are sent to the AI tool you asked, under your agreement with that provider (for example Anthropic or OpenAI). Junction itself runs no AI model and does not store the answers. Check your AI provider's business terms before connecting sensitive data; payroll and personal records are excluded by default.

Do I need a developer to use a construction MCP server?

Not with Junction. During early access we set the connection up with you. After that, each person adds one address to Claude or ChatGPT and signs in.

Is there an MCP server for my construction software?

Junction is one MCP server for many construction systems, including Viewpoint Vista, Trimble Spectrum, Sage 300 CRE, Foundation, CMiC, ComputerEase, QuickBooks Desktop, Autodesk Build and e-Builder. It is in early access, and each system goes live with a design partner who runs it. Primavera P6, Aconex, Fieldwire and about twenty more are next, and 200 systems are on the roadmap.