Sounds mostly correct. The standard LLM tool call 'shape' matches the MCP tool call 'shape' very closely. It's really just a simple standard to support connecting a tool to an agent (and by extension an LLM).
There are other aspects, like Resources, Prompts, Roots, and Sampling. These are all relevant to that LLM<->Agent<->Tools/Data integration.
As with all things AI right now, this is a solution to a current problem in a fast moving problem space.