> This is 100% a problem with the MCP spec: it does not currently provide a way to narrow what tools, and therefore context, flow into the LLM.

it's not the business of MCP spec, it should be task/job level, different task may need different tools and MCP just supply entire tools it has. The tool pickup should be the take charge by llm. moreover maybe some has `while list` to include or exclude some tools, but it should not from MCP spec.