Visual Studio Weekly: Custom Agents, MCP Governance, and Performance Upgrades

Visual Studio 2026's March update (18.4.0) dropped on March 10, and it's one of those releases where every section has something meaningful. Custom agents are here. MCP governance is buttoned up for enterprise. Debugging got smarter with Copilot. And MSVC v14.51 preview delivers measurable runtime performance gains. Let me walk through what shipped and what it means for your workflow. Build Your Own Custom Agents The biggest feature: you can now define custom Copilot agents as .agent.md files in your repository. These aren't just prompt templates. Custom agents get full workspace awareness, code understanding, tool access, and MCP connections to external knowledge sources like internal docs, design systems, or databases. Drop them in .github/agents/ and they show up in Visual Studio's agent picker: your-repo/ └── .github/ └── agents/ └── code-reviewer.agent.md ``` ` I've been experimenting with custom agents for context-specific workflows: PR reviewers wired to ADR repos via MCP, plann