World's Fair 2025
Full Spec MCP: Hidden Capabilities of the MCP spec — Harald Kirschner, Microsoft/VSCode
Overview
This talk explores the underutilized capabilities of the Model Contract Protocol (MCP) beyond basic tool calling. It highlights how embracing the full MCP specification can unlock richer, stateful interactions for AI agents. The presentation emphasizes that while many are shipping products quickly using only tools, the spec offers advanced features like dynamic discovery, resources, and sampling that enable more sophisticated agent behavior and development experiences.
Who should watch
- AI Engineers
- Product Managers
- Developers building AI-powered applications
- Anyone interested in advancing agent capabilities beyond simple function calls
- Those facing challenges with tool management and AI confusion in complex scenarios
Key takeaways
- The MCP ecosystem is rapidly growing but still in its early stages, with many advanced features yet to be widely adopted.
- Focusing solely on tool calling, while providing immediate success, leads to quality issues like AI confusion due to too many or poorly defined tools.
- Full MCP spec support enables stateful interactions, where agents can dynamically adapt to context, such as displaying relevant tools only when needed (e.g., a battle tool appearing only when a monster is present in a game).
- Resources within MCP can provide semantic layers for LLMs and users, allowing for actions like returning file references or exposing screenshots.
- Sampling, a feature allowing servers to request LLM completions from clients, is implemented but underutilized, offering potential for tasks like summarizing resources or formatting fetched web content.
- Developer experience for MCP servers is improving with features like dev mode and debugging in VS Code, making it easier to build and troubleshoot.
- Staying updated with the latest spec drafts and providing feedback is crucial for evolving MCP and ensuring features become stable and robust.
- Community efforts like a registry for MCP servers and new features like elicitations (tools requesting user input) are paving the way for more powerful and interactive agents.
Notable quotes
*The message is if you go with full MCP spec support, you will can unlock these rich stateful interactions that MCP vision is really outlining on how agents should work together.*
*It's really quality over quantity and clients handle that somewhat.*
*Sampling is one of the oddly named primitives as well. And if it had a better name, maybe more people would use it.*
Unofficial community note. Prefer the recording for nuance.