Problem

Scripts and CLIs can detect CI environments via the CI=true convention, enabling non-interactive behavior and CI-appropriate output. There's no equivalent for AI coding agents.

When agents execute commands, scripts have no way to know they're running in an agent context. This matters because:

• Error output — Agents benefit from structured errors (JSON with actionable suggestions) rather than human-friendly prose
• Verbosity — Agents can process more context; humans need scannable output
• Interactivity — Like CI, agents can't respond to prompts, but the existing CI=true doesn't capture the full picture

Use cases

# Script adapts output format
if [[ -n "${AGENT:-}" ]]; then
  echo '{"error": "config_missing", "suggestion": "run ./setup.sh", "docs": "https://..."}'
  exit 1
else
  echo "Error: Config file not found. Run ./setup.sh to initialize."
  exit 1
fi

# Test runner provides richer failure context for agents
if [[ -n "${AGENT:-}" ]]; then
  pytest --tb=long --verbose "$@"
else
  pytest "$@"
fi

Proposal

Agents set an environment variable when executing commands:

Adoption

AGENT variable (this proposal)

Tool-specific variables (status quo)

Consumer-side detection

Tools already adapting behavior based on agent detection:

Both had to build detection matrices because no single standard exists.

Precedent

• CI=true — Set by GitHub Actions, GitLab CI, CircleCI, Travis, Jenkins, etc.
• NO_COLOR=1 — Disables color output across CLIs (no-color.org)
• TERM=dumb — Signals limited terminal capabilities
• InfoQ: Patterns for AI Agent Driven CLIs — Recommends --no-interactive flags and structured output, but no env var convention

The CI convention emerged organically as tools independently adopted it. A coordinated standard would accelerate adoption for agents.

Open questions

1. Variable name — AGENT (Goose, Amp, Bun), AI_AGENT (Vercel's detect-agent), or something else? AGENT is concise and mirrors CI, but could collide with non-AI agent systems. AI_AGENT is more specific but verbose.
2. Scope — Should this cover all automation (like CI) or specifically AI agents?
3. Relationship to CI — Should agents also set CI=true, or is this orthogonal?
4. Coexistence — Should tools set both the standard variable AND their tool-specific one? (Goose already does: AGENT=goose + GOOSE_TERMINAL=1)

Known opposition

Prior art

• OpenAI Codex uses CODEX_SANDBOX=1 internally for sandbox detection
• Claude Code uses CLAUDECODE=1 paired with CLAUDE_CODE_ENTRYPOINT=cli

Comments welcome to update the adoption tables.