At least when working with local MCP servers I solved this problem by wrapping the mcp tools inside an in-memory cache/store. Each tool output gets stored under a unique id and the id is returned with the tool output. The agent can then invoke other tools by passing the id instead of generating all the input. Adding attribute access made this pretty powerful (e.g. pass content under tool_return_xyz.some.data to tool A as parameter b). This saves token costs and is a lot faster. Granted, it only works for passing values between tools but I could imagine an additional tool to pipe stuff into the storage layer would solve this.