v0.87.0 failed to start Nushell MCP

[hongquan]

Description

Since v0.87.0, Crush failed to start Nushell MCP. It is still working in v0.86.0

The MCP part in Crush config:

  "mcp": {
    "nu-mcp": {
      "type": "stdio",
      "command": "nu",
      "args": [
        "--mcp"
      ]
    },
    "mozilla-mdn": {
      "type": "http",
      "url": "https://mcp.mdn.mozilla.net/"
    },
    "pctx": {
      "type": "stdio",
      "disabled": true,
      "command": "pctx",
      "args": [
        "mcp",
        "start",
        "--stdio"
      ]
    }
  },

Here is v0.86.0

Related logs:

2026/07/25 13:48:31 INFO Initializing MCP clients source=github.com/charmbracelet/crush/internal/agent/tools/mcp/init.go:206
...
2026/07/25 13:48:31 DEBU MCP client initialized name=nu-mcp source=github.com/charmbracelet/crush/internal/agent/tools/mcp/init.go:539
2026/07/25 13:48:33 DEBU No MCPs allowed agent=Task source=github.com/charmbracelet/crush/internal/agent/coordinator.go:772 tool=mcp_nu-mcp_command_help
2026/07/25 13:48:33 DEBU No MCPs allowed agent=Task source=github.com/charmbracelet/crush/internal/agent/coordinator.go:772 tool=mcp_nu-mcp_command_help

Here is v0.87.0

Related logs:

2026/07/25 13:54:59 ERRO MCP client failed to initialize error="connection closed: calling \"initialize\": client is closing: EOF" name=nu-mcp source=github.com/charmbracelet/crush/internal/agent/tools/mcp/init.go:703
2026/07/25 13:54:59 DEBU Failed to initialize MCP client error="connection closed: calling \"initialize\": client is closing: EOF" name=nu-mcp source=github.com/charmbracelet/crush/internal/agent/tools/mcp/init.go:286

Version

v0.87.0

Environment

$os:Linux $os_distro:Ubuntu $os_version:26.04 GOARCH:amd64 GOOS:linux GoVersion:go1.26.5 NonInteractive:false SHELL:fish TERM:xterm-ghostty

[hongquan]

It seems that Nushell in stdio MCP does not support "initialize" message.
If run Nushell MCP in HTTP transport, Crush v0.87.0 can connect just fine.