# mcp.server.describeStartupFailure

**MCP concept example** A working example of the core library. It can change without notice.

- **Module:** mcp.server
- **Package:** @libtmux/mcp
- **Language:** TypeScript
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-ts/blob/46cccfef2a546de55ce8b308249b8c76339089a0/packages/mcp/src/server.ts#L317
- **Page:** https://libtmux.org/en/ts/latest/mcp/reference/mcp-server-describestartupfailure/

```
function describeStartupFailure(
  error: unknown,
  environment: Readonly<
    Record<string, string | undefined>
  > = process.env,
): string
```

One actionable line for a failure that happened before serving began.

stdout is the protocol, so stderr is the whole diagnostic channel, and an MCP
client surfaces it as the reason a server would not start. `spawn`/`ENOENT`
is separated because Node reports it as `spawn tmux ENOENT`, which reads as
tmux refusing rather than tmux being absent.

## Parameters

- `error` (`unknown`)
- `environment` (`Readonly<Record<string, string | undefined>>`)
  Default: `process.env`.