mcp-builder-ms — independently scanned and version-tracked by SaferSkills.
SaferSkills independently audited mcp-builder-ms (Agent Skill) and scored it 100/100 (green). The audit ran 55 deterministic rules across Security, Supply Chain, Maintenance, Transparency, and Community; it found 0 high-severity and 0 lower-severity findings. The full rule-by-rule trace and per-finding evidence are below. Free, methodology-open.
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Every scanned point with the score it earned and what moved between them.
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The primary manifest — the file an agent reads to learn what this artifact does.
Use this skill when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).
Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks.
Microsoft provides extensive MCP infrastructure for Azure and Foundry services. Understanding this ecosystem helps you decide whether to build custom servers or leverage existing ones.
| Type | Transport | Use Case | Example |
|---|---|---|---|
| Local | stdio | Desktop apps, single-user, local dev | Azure MCP Server via NPM/Docker |
| Remote | Streamable HTTP | Cloud services, multi-tenant, Agent Service | https://mcp.ai.azure.com (Foundry) |
Before building a custom server, 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 |
Full ecosystem: See 🔷 Microsoft MCP Patterns for complete server catalog and patterns.
| 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) |
| Extending Azure MCP | Follow Microsoft MCP Patterns |
Creating a high-quality MCP server involves four main phases:
#### 1.1 Understand Modern MCP Design
API Coverage vs. Workflow Tools: Balance comprehensive API endpoint coverage with specialized workflow tools. Workflow tools can be more convenient for specific tasks, while comprehensive coverage gives agents flexibility to compose operations. Performance varies by client—some clients benefit from code execution that combines basic tools, while others work better with higher-level workflows. When uncertain, prioritize comprehensive API coverage.
Tool Naming and Discoverability: Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes (e.g., github_create_issue, github_list_repos) and action-oriented naming.
Context Management: Agents benefit from concise tool descriptions and the ability to filter/paginate results. Design tools that return focused, relevant data. Some clients support code execution which can help agents filter and process data efficiently.
Actionable Error Messages: Error messages should guide agents toward solutions with specific suggestions and next steps.
#### 1.2 Study MCP Protocol Documentation
Navigate the MCP specification:
Start with the sitemap to find relevant pages: https://modelcontextprotocol.io/sitemap.xml
Then fetch specific pages with .md suffix for markdown format (e.g., https://modelcontextprotocol.io/specification/draft.md).
Key pages to review:
#### 1.3 Study Framework Documentation
Language Selection:
| Language | Best For | SDK |
|---|---|---|
| TypeScript (recommended) | General MCP servers, broad compatibility | @modelcontextprotocol/sdk |
| Python | Data/ML pipelines, FastAPI integration | mcp (FastMCP) |
| C#/.NET | Azure/Microsoft ecosystem, enterprise | Microsoft.Mcp.Core |
Transport Selection:
| Transport | Use Case | Characteristics |
|---|---|---|
| Streamable HTTP | Remote servers, multi-tenant, Agent Service | Stateless, scalable, requires auth |
| stdio | Local servers, desktop apps | Simple, single-user, no network |
Load framework documentation:
For TypeScript (recommended):
https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.mdFor Python:
https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.mdFor C#/.NET (Microsoft ecosystem):
~30 seconds. Free. No account. Every finding cites a rule and a line of evidence.