MCP Dev Summit North America

Before MCP, Arcade was building tools for LLM agents. We've shipped over 1,000 tools—first as native Arcade tools with our own protocol and eventually adopting MCP. The main lesson: the hard part isn't writing the code, it's finding the right abstraction.

Most MCP tools today are thin wrappers around APIs. `GET /users/{id}` becomes `get_user(id)`. But this creates a mismatch—LLMs reason about tasks ("find the customer who complained last week"), not endpoints. The question is: where should tools sit on the abstraction spectrum?

**Too low-level:** The agent needs to chain together many calls. Each step is a chance to fail, and the model has to maintain context across all of them. You're asking the LLM to be a programmer at runtime.

**Too high-level:** You end up enumerating every possible task as its own tool. This defeats the point of having a general-purpose agent and your tool schema balloons, eating context and degrading selection accuracy.


In this talk:

- The common pitfalls we see in MCP tool design
- Our design philosophy for optimized tools
- Multiple real-world use cases and the tools that work for them
- Outlook on future tool development