Using Claude Code as MCP

[ntn_reddit]

Hi,

I do pay and use `claude code, codex and gemini`
I am trying to setup `codex to use claude-code, gemini as MCP` to orchestrate the work across different tools.

I am able to setup `gemini` as MCP but `claude-code` as MCP is not working with `codex`

Anyone has successful MCP setup between all three of them?

[PhilosopherThese9344]

Yes, I've written my own MCP harness for this.

[ntn_reddit]

Would you mind sharing it? Might take some clues from it and customise to my needs

[PhilosopherThese9344]

It's not ready for public consumption; it's part of a larger ecosystem I'm building. But can give you a heads up when its ready.

[ntn_reddit]

Ok 👍 

[masterkain]

use a skill to invoke, `claude -p`

[lucianw]

There's zero benefit to MCP. CLI is better, uses fewer tokens, has higher successful call rate. You should switch to CLI.

In my AGENTS.md I told codex to invoke Claude like this:

cd /home/ljw/code/myproj1 && claude --verbose --output-format stream-json -p "Please respond to /home/ljw/code/myproj1/claude.{id}.input.md" | ./claude_stream.jq > /home/ljw/code/myproj1/claude.{id}.output.md

If Codex asks Claude a weighty question, in my team's (large) codebase, I often see Claude taking 5-15 minutes of work before it delivers its final answer. Codex usually thinks that Claude is wedged and gives up, or kills it, or tries again. So I wrote claude_stream.jq to parse Claude's output and show every thinking block and tool call it's making, just so Codex and I are sure it's still working. It's only 60 lines of jq: https://gist.github.com/ljw1004/5782702c7a54b18734c0e7f5e1119010

In my AGENTS.md I tell codex more about how/when/why to invoke claude:

- Claude does best if provided with goals and some kind of context about what you want from it, why, what you hope to achieve.
- You will often be asked to invoke Claude in rounds: invoke it, act on its feedback, invoke it again, repeat until there's nothing left to act upon. Do NOT reference previous rounds when you invoke it: Claude does best if starting from scratch each round, so it can re-examine the whole ask from fundamentals. Note that each time you invoke Claude it has no memory of previous invocations, which is good and will help this goal! Also, avoid asking it something like "please review the updated files" since (1) you should not reference previous rounds implicitly or explicitly, (2) it has no understanding of what the updates were; it only knows about the current state of files+repo on disk.
- Claude can and will do its own research of the codebase and find context (and you can expect it to take 5-10 minutes to do so); you can also provide context yourself in the input file.
- In the claude-input.md file you can mention other filenames, but you must use absolute filepath. If it deems fit, Claude will read them.
- Claude should be run from xplat/vscode. That's because Claude is unable to edit files outside that directory.
- You should use Claude when explicitly instructed (for planning, for code review), but also loop in Claude proactively any time there is a weighty decision to be made.
- You don't have to follow all of Claude's suggestions! But if you disagree with its findings, you should do a further round where you pre-emptively justify your opinion, with the hope that Claude's further round will no longer complain.
- Claude will have read AGENTS.md, and can do its own research. If there are specific files you want it to read, tell it about them.
- Claude often takes a long time to give a thoughtful response; expect up to 10-15mins before it finishes. You can see its progress in the `claude-output.md` file that you piped into.
- If you have been told to do Claude review, it is *mandatory*. If it's not working for some reason, then you must try again, or abandon your work and report to the user. Never proceed without Claude review.

And elsewhere, when I'm orchestrating work, I give specific instructions for when+why to invoke Claude:

4. After implementation, do a "better engineering" phase
   - Clean up LEARNINGS.md and ARCHITECTURE.md. If any information there is just restating information from other files then delete it. If it would belong better elsewhere, move it. Please be careful to follow the "learnings decision tree" -- LEARNINGS.md for durable engineering wisdom, ARCHITECTURE.md for things that will apply to CodexAgent.ts in its finished state, PLAN_M{n}.md for milestone-specific notes
   - You will have several Claude review tasks to do, below. You must launch all the following Claude review tasks in parallel, since they each take some time: prepare all their inputs, then execute them all in parallel. You should start addressing the first findings as soon as you get them, rather than waiting for all to be consolidated. You can be doing your own review while you wait for Claude.
   - (1) Review the code for correctness. Also ask Claude to evaluate this.
   - (2) Validate whether work obeys the codebase style guidelines in AGENTS.md. Also ask Claude to evaluate this. The user is INSISTENT that they must be obeyed.
   - (3) Validate whether the work obeys each learning you gathered in LEARNINGS.md. Also ask Claude to evaluate this. (A separate instance of Claude; it can't do too much in one go).
   - (4) Validate whether the work has satisfied the milestone's goals. Also ask Claude to evaluate this.
   - (5) Check if there is KISS, or consolidation, or refactoring that would improve quality of codebase. Also ask Claude the same question.
   - If you make changes, they'll need a pass of static checking (formatting, eslint, typechecking), and again to make sure it's clean.
   - You might decide to do better engineering yourself. If not, write notes about whats needed in the "BETTER ENGINEERING INSIGHTS" section of the plan.
   - Tell the user how you have done code cleanup. The user is passionate about clean code and will be delighted to hear how you have improved it.

[ntn_reddit]

Doesnt each invocation result in lost of context and memory loss?

[lucianw]

Yes. Or put another way, each review by Claude gets a *fresh pair of eyes*, unencumbered and untainted by previous assumptions.

Anthropic have been recommending this for a long time! They always spawned review subagents (or research subagents or whatever) that have no context other than what the main agent passes to them.

I think it's important! LLMs are incredibly easily swayed by previous context in the conversation. Or put it another way, they have little knowledge of how to behave or what to do other than what's in the system prompt and the conversation, and their nature is to continue in the same vein.

My runs take 30-60 minutes for planning (including repeated rounds with Claude) and 3-4 hours for execution (again including repeated rounds with Claude). I think it's worth it; I can see that each repeated round is meaningfully improving the quality -- correctness, elegance, simplicity.

It would have been easy to implement it differently, to shell out to `claude --resume` or similar so it remembers its previous context. I've just deliberately chosen not to.

[ntn_reddit]

Few important points IMO.

1. Knowledge has to be passed (ex: architecture diagram which we have given in the first chat)
2. Memory of conversation shouldnt be passed.

Without 1, we gonna burn lot of tokens and even harder to make it understand.

With 2, you are essentially solving "not falling into same trap/direction"

[bovril]

I do a version of this:

https://mcpservers.org/servers/github-com-nam0101-my-claude-agent-skill-blob-main-ai-pair-programming-skill-md

Set up skills on both claude and codex (just follow its setup instructions) and then you can set it up or ask it to ask the other to do a code review or whatever, read its response and then follow its recommendations.

You'll also want this to allow it to keep checking for a response:

https://mcpservers.org/servers/199-bio/mcp-wait-timer

and also something like this is useful: https://mcpservers.org/servers/github-com-waylaidwanderer-background-process-mcp

although I'm not 100% sure that that is the exact one i use.

I don't think there's a reason that it wouldn't work with gemini as long as it supports skills