MCP has one thing going for it as an agentic API standard: token efficiency

The single-request-for-all-abilities model + JSON RPC is more token efficient than most alternatives. Less flexible in many ways, but given the current ReAct, etc. model of agentic AI, in which conversations grow geometrically with API responses, token efficiency is very important.

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ejholmes 2 hours ago | parent | next [-]

But they're not token efficient. Take the terraform example from the post. Plan JSON is massive. You're not saving tokens by using a Terraform MCP and shoving an entire plan into context. Composition allows for efficient token use.

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SOLAR_FIELDS 4 hours ago | parent | prev | next [-]

But the flip side of this is that the tools themselves take up a ton of token context. So if you have one mcp it’s great but there is an upper bound that you hit pretty quick of how many tools you can realistically expose to an agent without adding some intermediary lookup layer. It’s not compact enough of a spec and doesn’t have lazy loading built into it

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harrall 4 hours ago | parent [-]

Yes but I consider that just a bug in the agents that use MCP servers.

It could just be fixed to compress the context or the protocol could be tweaked.

Switching to CLIs is like buying a new car because you need an oil change. Sure, in this case, the user doesn’t get to control if the oil change can be done, but the issue is not the car — it’s that no one will do the relatively trivial fix.

	▲	dnautics 4 hours ago \| parent [-]
		you know what you could do? You could write a skill that turns mcps on or off!

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ako 4 hours ago | parent | prev [-]

I've been creating a cli tool with a focus on token efficiency. Dont see why cli could not be as token efficient as mcp. The cli has the option to output ascii, markdown and json.

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recursivedoubts 4 hours ago | parent | next [-]

I'm working on a paper on this, if you are using a hypermedia-like system for progressive revelation of functionality you are likely to find that this chatty style of API is inefficient compared with an RPC-like system. The problem is architectural rather than representational.

I say this as a hypermedia enthusiast who was hoping to show otherwise.

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bear3r 3 hours ago | parent | prev [-]

the output format (ascii/json/markdown) is one piece, but the other side is input schema. mcp declares what args are valid and their types upfront, so the model can't hallucinate a flag that doesn't exist. cli tools don't expose that contract unless you parse --help output, which is fragile.

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ako 3 hours ago | parent [-]

So far, cli --help seems to work quite well. I'm optimizing the cli to interact with the agent, e.g., commands that describe exactly what output is expected for the cli DSL, error messages that contain DSL examples that exactly describe the agent how to fix bugs, etc. Overall i think the DSL is more token efficient that a similar JSON, and easier to review for humans.

	▲	bear3r an hour ago \| parent [-]
		fair point on token efficiency -- dsls are usually tighter than json. where i see mcp still winning is tool discovery: the client learns what tools exist and what args they take without having to try calling them first or knowing the commands upfront. with cli you have to already know the tool exists.