alt Hacker NewsWhat do MCPs do that the CLI cannot?
i.e. assuming your agent has access to the terminal, and therefore CLIs, what additional value do MCPs provide?
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formerly_proven • yesterday at 11:52 AM
MCP can wrap things which have stateful processes, debuggers for example. Agents will use batch mode but it is quite limited and due to tool calls always being implemented as synchronous invocations, non-batch mode doesn’t work for tool calls. MCP solves this by giving the agent a handle it can use to refer to in multiple invocations.
Burns a lot of tokens though and if you need more than batch-mode gdb to debug something the chances of an agent solving it today are very slim.
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Out of curiosity, I put this exact question to claude [0]. Here's a tl;dr of its answer with my refutations:
> MCPs expose tools with defined schemas, parameters, and return types.
CLIs do exactly the same thing
> Stateful Connections
A chat session with an LLM is exactly that!
> MCPs can return structured data (JSON, complex objects)
So can an agent with a CLI. E.g. they can just take output and > file.json - now they have a json file.
> MCPs can expose "resources" - like file contents, database schemas, or API documentation - that I can read directly
If you mention these in your prompt to an agent, then they know where to look and can access them too (and use keys etc as necessary)!
> MCPs can send progress updates, ask for clarification, or stream results.
So can a chat session with an agent.
> MCPs can implement fine-grained permission controls and rate limiting at the protocol level.
Rate limiting is easy for an agent. Fine-grained permission could be limited by the user of the agent (e.g. by giving a restricted key for the agent to use), so possible if desired.
tl;dr no added benefit whatsoever.
[0] https://claude.ai/share/4b339fbd-a6db-4fcb-86cd-0e8493aab663