CLI for agents

Human-oriented CLIs often block agents: interactive prompts, huge upfront docs, and help text without copy-pasteable examples. Prefer patterns that work headlessly and compose in pipelines.

Non-interactive first

• Every input should be expressible as a flag or flag value. Do not require arrow keys, menus, or timed prompts.
• If flags are missing, then fall back to interactive mode—not the other way around.

Bad: mycli deploy → ? Which environment? (use arrow keys) Good: mycli deploy --env staging

Discoverability without dumping context

• Agents discover subcommands incrementally: mycli, then mycli deploy --help. Do not print the entire manual on every run.
• Let each subcommand own its documentation so unused commands stay out of context.

--help that works

• Every subcommand has --help.
• Every --help includes Examples with real invocations. Examples do more than prose for pattern-matching.

text
Options:
  --env     Target environment (staging, production)
  --tag     Image tag (default: latest)
  --force   Skip confirmation

Examples:
  mycli deploy --env staging
  mycli deploy --env production --tag v1.2.3
  mycli deploy --env staging --force

stdin, flags, and pipelines

• Accept stdin where it makes sense (e.g. cat config.json | mycli config import --stdin).
• Avoid odd positional ordering and avoid falling back to interactive prompts for missing values.
• Support chaining: mycli deploy --env staging --tag $(mycli build --output tag-only).

Fail fast with actionable errors

• On missing required flags: exit immediately with a clear message and a correct example invocation, not a hang.

text
Error: No image tag specified.
  mycli deploy --env staging --tag <image-tag>
  Available tags: mycli build list --output tags

Idempotency

• Agents retry often. The same successful command run twice should be safe (no-op or explicit "already done"), not duplicate side effects.

Destructive actions

• Add --dry-run (or equivalent) so agents can preview plans before committing.
• Offer --yes / --force to skip confirmations while keeping the safe default for humans.

Predictable structure

• Use a consistent pattern everywhere, e.g. resource + verb: if mycli service list exists, mycli deploy list and mycli config list should follow the same shape.

Success output

• On success, return machine-useful data: IDs, URLs, durations. Plain text is fine; avoid relying on decorative output alone.

text
deployed v1.2.3 to staging
url: https://staging.myapp.com
deploy_id: dep_abc123
duration: 34s

When reviewing an existing CLI

• Check: non-interactive path, layered help, examples on --help, stdin/pipeline story, error messages with invocations, idempotency, dry-run, confirmation bypass flags, consistent command structure, structured success output.