--- title: Nue MCP Servers Overview slug: nue-mcp-servers-overview createdAt: 2026-06-13T02:22:32.475Z --- **Model Context Protocol (MCP)** is an open specification (originally from [Anthropic](https://www.anthropic.com/)) that standardizes how AI models and agents connect to external **tools** — business logic, data sources, and services — through a simple request/response interface over HTTP or streaming transports. MCP allows AI clients to reliably **discover available tools**, call them with **structured parameters**, and receive **structured results**. Assistants can interact with real systems in a predictable, secure, and verifiable way, rather than relying solely on ungrounded natural language prompts. # Why MCP Matters By separating model-specific behavior from tool execution, MCP allows organizations to **keep domain logic in one place** and **reuse it across multiple LLMs** (e.g., OpenAI, Anthropic, Gemini) and agent runtimes. This reduces integration friction, avoids model lock-in, and makes AI integrations more scalable and maintainable. ## MCP Server: The Tool Execution Layer An **MCP Server** is any service that implements the [Model Context Protocol](https://www.anthropic.com/news/model-context-protocol) and exposes one or more **named tools** — each with clear descriptions and input schemas — that AI clients can call. At runtime, the MCP Server acts as the **execution layer**: it tells clients which tools are available, authenticates and authorizes incoming requests, runs the requested business logic (e.g., calling APIs, querying databases), and streams back structured results. The server itself remains **model-agnostic** — it doesn't depend on a specific LLM. All model-specific reasoning happens on the client side. **Key responsibilities of an MCP Server:** - **Advertise available tools** to clients (including name, description, and parameter schema) for safe discovery. - **Receive structured tool calls** over JSON-RPC or streaming HTTP/SSE, execute the underlying logic, and return results or errors in a predictable format. - **Enforce authentication and authorization**, ensuring the right data and tools are accessible with the right scope. ## MCP Client: The AI Integration Layer An **MCP Client** runs inside your AI application or agent framework. It connects to one or more MCP Servers, retrieves their tool definitions, and makes them available to the model as part of its prompt and function-calling context. When the model chooses to call a tool, the MCP Client translates that intent into a structured request (e.g., HTTP/SSE), manages retries and timeouts, and streams the response back to the model for further reasoning. ![](https://api.archbee.com/api/optimize/fHNLtQ9NwpgDvkWodNqKf/Bn0W3UGufKAPFAcPi2wid_image.png) # The Nue MCP Gateway Nue exposes its revenue platform through a **single MCP endpoint — the Nue MCP Gateway** — that federates a set of specialized, domain-focused servers behind one authenticated connection. You connect once (see [Connecting to Nue MCP](docId\:H6afI-jEH6817eW0vD13w)); the gateway advertises the combined tool set, routes each call to the right server, and **namespaces** tools per server (e.g. `lcm_`, `nuedocs_`, `pricebuilder_`) so they never collide. | Nue Environment | Gateway endpoint | | --------------- | -------------------------------- | | Nue Production | `https://mcp.nue.io/mcp` | | Nue Sandbox | `https://mcp.sandbox.nue.io/mcp` | ## Built-in servers (on by default) Three servers are built into the gateway and **enabled by default** — connect once and they're ready, no extra setup: | Server | Coverage | Status | | ----------------------------------------------------- | ------------------------------------------------------------------------------------ | ---------- | | [Nue Lifecycle Manager](docId\:Cf8cbHyGYpD3OZg7Ym2GY) | Opportunities · Quotes · Orders · Subscriptions · Renewals · Invoices · Credit memos | Default-on | | [Nue Docs](docId\:DPlnzHFZgELTbUrSoLBu2) | Search & read the Knowledge Center and REST API reference | Default-on | | [Nue Price Builder](docId\:VMvBd0nkai8uVh0rkvyls) | Products · Pricing rules · Bundles · Pricing plugins · SKU config | Default-on | ## Available servers (opt-in) Two further servers are available and can be switched on by an administrator from the MCP Servers list in your tenant. They are **not connected by default**, because the work they cover is administrative and financial rather than everyday selling: | Server | Coverage | Status | | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------- | ------ | | [Nue Billing & Collections](docId\:tDCeaHa5hS6AD913sa3cI) | Invoices · Credit & debit memos · Payments · Billing schedules · Collections · Stripe integration | Opt-in | | [Nue Admin](docId:-WRaw4P_LcND4UfXUv8nw) | System settings · Data imports & exports · Webhook endpoints | Opt-in | One more domain is on the roadmap: | Server | Coverage | Status | | ---------------- | -------------------------------------------------- | ------- | | **Analytics** 🚧 | ARR · MRR · Churn · Forecasting · Revenue insights | Roadmap | You can also add your own [External MCP Servers](docId\:TAssMkgQ9g_37SfC0Hzjz) — Sigma, Gong, Fellow, or any MCP-compliant tool — so Nue's agents (and your own) can reach into the rest of your stack. Built-in servers are always on; the opt-in Nue servers above and any external servers are enabled and managed per org. # Why Nue uses MCP this way Nue MCP Servers are intelligent, model-agnostic orchestration layers that connect your revenue data with AI — securely and seamlessly. By exposing Nue's APIs through standardized MCP tools rather than custom prompts or hard-coded integrations, Nue gets three durable properties: - **Domain logic stays in the platform.** Pricing math, term calculations, proration, tax — all computed by Nue's APIs and returned as structured results. The model decides *what* to do; the platform decides *how*. This is what makes Nue AI's transactions safe from hallucination. - **Tools are reusable across any AI client.** The same MCP servers power Nue AI inside the platform *and* connect to external MCP clients (ChatGPT, Codex, Claude, Claude Code, Cursor, custom agents). With per-user **OAuth**, connecting is one click — you sign in through your browser and the assistant acts as you. Your investment in tools and guardrails carries over. See [Connecting to Nue MCP](docId\:H6afI-jEH6817eW0vD13w). - **One gateway, specialized servers.** A single endpoint keeps connection simple, while per-domain servers scope tool sets by intent, allow per-server governance, and let each domain evolve independently. # Related - [Connecting to Nue MCP](docId\:H6afI-jEH6817eW0vD13w) — the recommended one-click, per-user way to connect the Nue MCP Gateway from ChatGPT, Codex, Claude, Claude Code, and other clients. - [Nue Lifecycle Manager](docId\:Cf8cbHyGYpD3OZg7Ym2GY) — create opportunities, quotes, and orders, and manage the customer lifecycle (subscriptions, invoices, and credit memos). - [Nue Docs](docId\:DPlnzHFZgELTbUrSoLBu2) — search and read the Knowledge Center and REST API reference. - [Nue Price Builder](docId\:VMvBd0nkai8uVh0rkvyls) — tools and setup for products, pricing rules, bundles, and pricing plugins. - [Nue Billing & Collections](docId\:tDCeaHa5hS6AD913sa3cI) — invoicing, credit and debit memos, payments, billing schedules, collections, usage, and the Stripe integration. - [Nue Admin](docId:-WRaw4P_LcND4UfXUv8nw) — tenant system settings, data imports and exports, and webhook endpoints. - [External MCP Servers](docId\:TAssMkgQ9g_37SfC0Hzjz) — connect any MCP-compliant tool to extend Nue's reach. - [Meet Nue AI](https://docs.nue.io/c-SM-nue-ai) — the platform overview and what makes Nue AI different.