mcp-builder

# MCP Server Development Guide > Build high-quality MCP servers that enable LLMs to interact with external services > **Staleness Watch**: See [EXTERNAL-API-REGISTRY.md](../../EXTERNAL-API-REGISTRY.md) for source URLs and recheck cadence The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks. --- ## When to Build vs Use Existing ### Microsoft MCP Servers Before building custom, check if Microsoft already provides one: | Server | Type | Description | |--------|------|-------------| | **Azure MCP** | Local | 48+ Azure services (Storage, KeyVault, Cosmos, SQL, etc.) | | **Foundry MCP** | Remote | `https://mcp.ai.azure.com` - Models, deployments, evals, agents | | **Fabric MCP** | Local | Microsoft Fabric APIs, OneLake, item definitions | | **Playwright MCP** | Local | Browser automation and testing | | **GitHub MCP** | Remote | `https://api.githubcopilot.com/mcp` | ### Decision Matrix | Scenario | Recommendation | |----------|----------------| | Azure service integration | Use **Azure MCP Server** (48 services covered) | | AI Foundry agents/evals | Use **Foundry MCP** remote server | | Custom internal APIs | Build **custom server** (this guide) | | Third-party SaaS integration | Build **custom server** (this guide) | --- ## Server Types | Type | Transport | Use Case | Example | |------|-----------|----------|---------| | **Local** | stdio | Desktop apps, single-user, local dev | Azure MCP Server via NPM/Docker | | **Remo...