MCP Server .NET 10

A Model Context Protocol (MCP) server for the insurance domain, built with .NET 10 and the official MCP C# SDK. It lets AI assistants such as GitHub Copilot, Claude, or any MCP client manage insurance policies through tools, prompts and resources.

Storage is pluggable through the Persistence:Provider setting: an in-memory store (the default, no database needed) or PostgreSQL. Both are seeded with the same sample policies (e.g. POL-2025-000101).

Features

Validation failures and unknown policies are returned as readable MCP errors, so the model can correct itself.

Architecture

flowchart LR
    C[MCP clients<br/>Copilot · Inspector · Claude] -->|stdio| S[Host.Stdio]
    C -->|Streamable HTTP /mcp| H[Host.Http]
    S --> M[Mcp<br/>Tools · Prompts · Resources]
    H --> M
    M --> CO[Core<br/>PolicyService · rules]
    CO -->|IPolicyRepository| I[Infrastructure]
    I -->|Provider = InMemory| MEM[(In-memory store)]
    I -->|Provider = Postgres| DB[(PostgreSQL<br/>EF Core, database-first)]

• Core holds the domain model, business rules and the IPolicyRepository contract. It has no MCP or storage dependencies.
• Infrastructure implements the repository. Persistence:Provider selects the implementation at startup; nothing outside Infrastructure knows which one is in use.
• Mcp is a thin adapter: it maps MCP requests to Core and domain errors to MCP errors.
• Hosts only choose the transport. Both call WithInsuranceCapabilities(), so stdio and HTTP behave identically.

Project structure

src/
  BuildLogic45.Insurance.Core/            # Domain model, business rules, IPolicyRepository
  BuildLogic45.Insurance.Infrastructure/  # In-memory and PostgreSQL repositories, scaffolded EF Core model
  BuildLogic45.Insurance.Mcp/             # MCP tools, prompts and resources
  BuildLogic45.Insurance.Host.Stdio/      # stdio host
  BuildLogic45.Insurance.Host.Http/       # Streamable HTTP host (/mcp, /health)
database/
  postgres/                               # SQL scripts: create database, create tables, seed data
tests/
  BuildLogic45.Insurance.Core.Tests/              # Unit tests
  BuildLogic45.Insurance.Infrastructure.Tests/    # PostgreSQL repository tests (need a database)
  BuildLogic45.Insurance.Mcp.IntegrationTests/    # End-to-end tests with a real MCP client
.vscode/                                  # mcp.json (Copilot), launch.json (F5 debugging)
docker-compose.yml                        # Local PostgreSQL
dotnet-tools.json                         # dotnet-ef for scaffolding the EF Core model

Prerequisites

• [.NET SDK 10](https://dotnet.microsoft.com/download/dotnet/

... View full README on GitHub