setup mcp can brick Codex (invalid config: url is not supported for stdio) via add-mcp merge bug #163

Summary

firecrawl setup mcp can leave Codex completely unusable ("Error creating chat") when the machine has a leftover stdio-style firecrawl entry in ~/.codex/config.toml from the older firecrawl-mcp setup.

The root cause is not in this repo — setup mcp shells out to npx -y add-mcp, and add-mcp deep-merges the new server entry into an existing one with the same name instead of replacing it. The old stdio keys survive alongside the new remote ones:

[mcp_servers.firecrawl]
command = "npx"
args = [ "-y", "firecrawl-mcp" ]
type = "http"
url = "https://mcp.firecrawl.dev/<key>/v2/mcp"

  [mcp_servers.firecrawl.env]
  FIRECRAWL_API_KEY = "<key>"

Codex rejects the whole config file on this hybrid entry:

Error creating chat
invalid configuration: url is not supported for stdio
in `mcp_servers.firecrawl`

and every chat fails until the user hand-edits config.toml. Since your user base is exactly the population likely to have the old firecrawl-mcp stdio entry lying around, setup mcp is a common trigger for this even though the defect is upstream.

Repro

1. Have ~/.codex/config.toml (or CODEX_HOME) containing the classic stdio entry:

   [mcp_servers.firecrawl]
   command = "npx"
   args = [ "-y", "firecrawl-mcp" ]
   
     [mcp_servers.firecrawl.env]
     FIRECRAWL_API_KEY = "fc-test"

2. Run firecrawl setup mcp (or the equivalent npx -y add-mcp "https://mcp.firecrawl.dev/fc-test/v2/mcp" --name firecrawl --transport http -g -a codex -y).
3. Codex now fails to create any chat with the error above.

Observed with firecrawl-cli 1.19.6/1.19.27 and add-mcp 1.14.0 on macOS.

Status upstream

Fix submitted as neon-solutions/add-mcp#83 (replace server entries atomically on re-install instead of deep-merging). Since setup mcp invokes add-mcp unpinned via npx -y add-mcp, users get the fix automatically once it's merged and released — no change needed here in that case.

Possible mitigations in this repo

• Pin a minimum add-mcp version in the setup mcp shell-out once the fix ships (npx -y add-mcp@^1.x.y).
• Optionally have setup mcp detect/remove a stale stdio firecrawl entry before installing the remote one, which would also protect users of other agents' config files.