Show HN: Mcp2cli – One CLI for every API, 96-99% fewer tokens than native MCP

Original Article ↗ Hacker News Discussion ↗

Project concept and motivation

  • mcp2cli exposes MCP servers as CLIs so models can use “known” CLI patterns instead of full MCP schemas.
  • Key ideas mentioned: dynamic CLI generation from MCP/OpenAPI, lazy on-demand tool discovery, and caching of specs (default TTL ~1 hour).
  • Some see this as improving composability and aligning with agents that already write Bash well.

Token usage and performance concerns

  • Proponents emphasize large token savings because native MCP clients inject full tool schemas into context every turn, while a CLI lets the model discover tools progressively.
  • One explanation: with MCP, the entire tool list and schemas are repeatedly in context; with a CLI, the model calls --list or --help only when needed.
  • Critics argue token counts alone are not a meaningful metric; they want evidence that accuracy, latency, and error rates are comparable.
  • Doubts raised that short summaries can fully replace verbose JSON schemas without some accuracy loss.

MCP vs CLI vs “just HTTP/web”

  • Some question why MCP is needed at all given existing tools: HTTP APIs, OpenAPI, curl, SSH, and traditional CLIs.
  • Supporters of MCP highlight:
    • Granular authorization and OAuth instead of raw API keys.
    • Restricting what operations an agent can perform, not just which domains it can reach.
    • Structured validation, schemas, prompts, and resources, especially valuable for org-wide standardization, telemetry, and shared skills.
  • Others see MCP as over-engineered or a “reinvented OpenAPI,” arguing that harness-level sandboxing or direct CLIs could solve the same problems.

Tool discovery and routing

  • Multiple comments treat “always inject all MCP tools” as a client bug, not an MCP requirement.
  • Suggested fixes: tool routing/search sub-agents, RAG over tool descriptions, and Anthropic-style ToolSearchTool patterns.
  • Some worry that RAG-based tool selection requires extra model calls per request and might affect accuracy.

Ecosystem saturation and differentiation

  • Many similar MCP-to-CLI projects are listed; several people note there are “dozens” or “about 100” such tools already.
  • For small, simple use cases, some recommend just generating a custom CLI with an agent instead of adopting someone else’s.
  • Questions remain about how this project differs in practice from existing tools like mcporter, mcpshim, or other MCP CLIs.