This includes the attempted MCP installation command in the error output if the command fails. This should help users debug issues installing the MCP. In some cases, it may be enough for the user to simply run the command themselves manually. In particular, we've seen cases where tiger mcp install claude-code fails because claude isn't in the user's $PATH, because some (older?) Claude Code installation mechanisms create a bash alias for it instead of adding it to the $PATH. In that case, the user should be able to just run the command themselves manually to install the MCP.

I also modified the error to not include the command output if it's empty (as is the case when the executable can't even be found).

The error now looks like this if there's no output from the command:

$ tiger mcp install claude-code
Error: failed to add Tiger MCP server configuration: failed to run Claude Code installation command: exec: "claude": executable file not found in $PATH
Command: claude mcp add -s user tiger /Users/nathan/go/bin/tiger mcp start

And it looks like this if there is output:

$ tiger mcp install claude-code
Error: failed to add Tiger MCP server configuration: failed to run Claude Code installation command: exit status 1
Command: claude mcp add -s user tiger /Users/nathan/go/bin/tiger mcp start
Output: This is a failure

Closes AGE-225