Use cov-loupe CLI as a fallback when the MCP server is unavailable¶

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The cov-loupe application provides precise test coverage information for your Ruby application. It reads the .resultset.json file generated by SimpleCov and exposes that data through multiple subcommands.

Ideally it is configured as an MCP server so you can call its tools directly. If the MCP server is unavailable or errors prevent tool calls from succeeding, fall back to the CLI.

Fallback instructions¶

Detect the failure – if any MCP tool call fails or the server is unreachable, do not retry it or attempt to read .resultset.json manually. Switch to CLI mode immediately.
Run CLI commands using cov-loupe <subcommand> (or bundle exec exe/cov-loupe <subcommand> when running from a local gem checkout). The subcommands mirror the MCP tools:

MCP tool	CLI subcommand	Example
`project_coverage`	`list`	`cov-loupe list`
`file_coverage_summary`	`summary <path>`	`cov-loupe summary lib/foo.rb`
`file_coverage_raw`	`raw <path>`	`cov-loupe raw lib/foo.rb`
`file_uncovered_lines`	`uncovered <path>`	`cov-loupe uncovered lib/foo.rb`
`file_coverage_detailed`	`detailed <path>`	`cov-loupe detailed lib/foo.rb`
`project_coverage_totals`	`totals`	`cov-loupe totals`
`project_validate`	`validate <expr>`	`cov-loupe validate 'pct >= 90'`
`version`	`--version` (flag)	`cov-loupe --version`

Use --help at any point to get up-to-date flag and argument information:
```
cov-loupe --help
cov-loupe list --help
```
Treat CLI output as authoritative – do not estimate or infer coverage figures from source files or test files. All data must come from cov-loupe output.
Report the fallback – briefly note in your response that you used the CLI rather than the MCP server, so the user knows which mode was active.