Comparison table of CLI via subprocess versus MCP using standard JSON-RPC across six metrics. CLI has much lower startup token cost at about 0 to 200 tokens versus roughly 5,000 to 55,000 or more for MCP. CLI also has lower execution overhead at under 10 milliseconds versus 50 to 200 milliseconds for MCP. Data throughput is high for CLI using stdout streaming and low for MCP due to JSON pagination. Reliability is variable for CLI because parsing stdout can be brittle, while MCP reliability is high thanks to structured error handling. Output format efficiency is high for CLI because plain text is closer to LLM-native input, while MCP is lower because JSON is more verbose.