> easy tool calling for the LLM rather than having to figure out how to call the API based on docs only

I think the best way to run an agent workflow with custom tools is to use a harness that allows you to just, like, write custom tools. Anthropic expects you to use the Agent SDK with its “in-process MCP server” if you want to register custom tools, which sounds like a huge waste of resources, particularly in workflows involving swarms of agents. This is abstraction for the sake of abstraction (or, rather, market share).

Getting the tool built in the first place is a matter of pointing your agent at the API you’d like to use and just have them write it. It’s an easy one-shot even for small OSS models. And then, you know exactly what that tool does. You don’t have to worry about some update introducing a breaking change in your provider’s MCP service, and you can control every single line of code. Meanwhile, every time you call a tool registered by an MCP server, you’re trusting that it does what it says.

> authorization can be handled automatically by MCP clients. How are you going to give a token to your LLM otherwise??

env vars or a key vault

> And if you do, how do you ensure it does not leak the token?

env vars or a key vault