Design Principles: API vs MCP
As adoption of the Model Context Protocol (MCP) accelerates, many teams are building MCP servers using familiar API design patterns - CRUD-style tools, exposed resources, and thin wrappers over existing APIs. While this approach can function, it does not maximize the value MCP is designed to unlock. MCP is not an API replacement; it introduces a different model built around capabilities, constraints, and agent-driven orchestration.
This talk explains why API-oriented designs limit MCP’s effectiveness, even when they “work”. We’ll contrast traditional API principles, where deterministic clients orchestrate workflows with MCP design principles, where autonomous agents reason over narrowly scoped capabilities. Using vendor-neutral examples from deployment and operations workflows, I’ll show how to design MCP tools that are minimal, safe, and agent-native, and clarify when MCP provides more value than an API.
Many organizations are approaching MCP server design by exposing existing APIs through MCP with minimal adaptation. The result is often a collection of CRUD tools, thin API wrappers, and overly broad capabilities that technically function but provide limited value to AI agents.
This session examines the architectural differences between traditional APIs and MCP and explains why design approaches that work well for human-operated systems frequently become anti-patterns when applied to agent-driven workflows.
The talk introduces four practical MCP design principles:
- Capabilities, Not Primitives
- Intent-Based Interfaces
- Minimal Capability Surfaces
- Observable Operational Intent
Attendees will see how these principles influence tool design, authorization models, operational safety, and agent reasoning. The session also explores common MCP anti-patterns, including CRUD tools, thin API wrappers, and overexposed power, demonstrating how they increase complexity and reduce the effectiveness of AI agents.
Rather than focusing on a specific vendor, framework, or implementation, the talk uses real-world deployment and operations scenarios to illustrate the concepts. Attendees will leave with a practical framework for deciding when MCP is appropriate, how to structure MCP tools effectively, and how to build systems that are both agent-friendly and operationally safe.
This session is intended for platform engineers, API designers, infrastructure engineers, and developers who are building or evaluating MCP servers and want to move beyond simply exposing existing APIs to creating truly agent-native capabilities.
Security focused Software Engineer and Developer Advocate from a DevOps background with over a decade of experience spanning multiple sectors. Idea incubator, big picture thinker and security innovator. Builder of OSS tools to empower developers to be secure by default. On a mission to lower developer’s barriers to entry for security, remove passwords from workloads, and enable the next generation of engineers to further advance the security industry.