Try it

Every example on this page is a live ruleset at api.aethis.ai. Anonymous /decide accepts a public ruleset_id or slug; composed rulebook_id lookups need an x-api-key header — see Nomenclature.

This page leads with curl because every example is reachable with zero install. The same calls work from the CLI (aethis decide -b <slug> -i '{...}'), the Python SDK (client.decide(...)), or via a coding agent through MCP (“Use Aethis to decide …”). The Evaluate a case recipe shows the same call across all four interfaces side-by-side.

UK Free School Meals — the canonical worked example

Three composed sections (age + school type gate, household means-test, universal infant route). Represents the “rules compiled from legislation” pattern in one compact case.

Section A — child eligibility (anonymous)

# State-funded Year 5 child, age 10 — Section A alone
curl -X POST https://api.aethis.ai/api/v1/public/decide \
  -H "Content-Type: application/json" \
  -d '{
    "ruleset_id": "aethis/uk-fsm/child-eligibility",
    "field_values": {
      "child.age": 10,
      "child.school_type": "state_funded"
    }
  }'
# → "decision": "eligible"

Sections B (household means-test) and C (universal infant)

Sections B and C are rulesets within the aethis/uk-fsm rulebook. They are also published as standalone slugs (aethis/uk-fsm/household-criteria, aethis/uk-fsm/universal-infant), and are combined with Section A via the rulebook’s outcome_logic — see the composed-rulebook call below for the full evaluation that exercises all three.

The composed rulebook (`A AND (B OR C)`) — requires an API key

curl -X POST https://api.aethis.ai/api/v1/public/decide \
  -H "Content-Type: application/json" \
  -H "x-api-key: $AETHIS_API_KEY" \
  -d '{
    "rulebook_id": "aethis/uk-fsm",
    "field_values": {
      "child.age": 10,
      "child.school_type": "state_funded",
      "child.year_group": "year_5",
      "household.receives_universal_credit": true,
      "household.annual_net_earnings": 6000,
      "household.receives_income_support": false,
      "household.receives_income_based_jsa": false,
      "household.receives_income_related_esa": false,
      "household.receives_child_tax_credit_only": false,
      "household.receives_nass_support": false,
      "child.is_looked_after": false,
      "child.is_care_leaver": false
    }
  }'
# → "decision": "eligible" with per-section breakdown

Inspect Section A on its own:

curl https://api.aethis.ai/api/v1/public/rulesets/aethis/uk-fsm/child-eligibility/schema
curl https://api.aethis.ai/api/v1/public/rulesets/aethis/uk-fsm/child-eligibility/explain

Spacecraft Crew Certification Act 2049 — the demo rule

Synthetic but carefully built to exercise ENUM, date, and exception-chain logic. Great for agents learning the tool.

curl -X POST https://api.aethis.ai/api/v1/public/decide \
  -H "Content-Type: application/json" \
  -d '{
    "ruleset_id": "aethis/spacecraft-crew-certification",
    "field_values": {
      "space.crew.species": "Vogon"
    },
    "include_trace": true
  }'
# → "decision": "not_eligible" — Vogons are disqualified under Section 3(1)

curl https://api.aethis.ai/api/v1/public/rulesets/aethis/spacecraft-crew-certification/schema

Construction All Risks insurance — the adversarial benchmark

Five levels of nested exceptions from a real Construction All Risks (CAR) policy. The kind of deeply nested rule that trips up frontier LLMs on a bad run — and the engine gets right, deterministically, every time.

curl https://api.aethis.ai/api/v1/public/rulesets/aethis/construction-all-risks/schema

See the CAR benchmark narrative for the full “LLMs get it wrong, compiler gets it right” story.

Consumer credit prequalification

Affordability checks with numeric thresholds + soft-fail paths.

curl https://api.aethis.ai/api/v1/public/rulesets/aethis/consumer-credit-prequalification/schema

List every live ruleset

curl https://api.aethis.ai/api/v1/public/rulesets

Returns all currently-active public rulesets with their slugs, human-readable names, and rule counts. Always reference a ruleset by its slug (e.g. aethis/uk-fsm/child-eligibility); the dated ruleset_id underneath rotates on every regeneration but the slug stays stable. See Decision envelope for the version-pin story.

Next steps

MCP server — wire the same rulesets into Claude Code / Cursor / Windsurf
CLI — uv tool install aethis-cli && aethis decide -b aethis/uk-fsm/child-eligibility ...
REST API — full endpoint reference
Author your own rules — invite-only private beta

Getting started (no key)

AI coding agents

Interfaces

Recipes

Authoring (invite-only)

Reference

Changelog

UK Free School Meals — the canonical worked example

Section A — child eligibility (anonymous)

Sections B (household means-test) and C (universal infant)

The composed rulebook (`A AND (B OR C)`) — requires an API key

Spacecraft Crew Certification Act 2049 — the demo rule

Construction All Risks insurance — the adversarial benchmark

Consumer credit prequalification

List every live ruleset

Next steps

​UK Free School Meals — the canonical worked example

​Section A — child eligibility (anonymous)

​Sections B (household means-test) and C (universal infant)

​The composed rulebook (A AND (B OR C)) — requires an API key

​Spacecraft Crew Certification Act 2049 — the demo rule

​Construction All Risks insurance — the adversarial benchmark

​Consumer credit prequalification

​List every live ruleset

​Next steps

UK Free School Meals — the canonical worked example

Section A — child eligibility (anonymous)

Sections B (household means-test) and C (universal infant)

The composed rulebook (`A AND (B OR C)`) — requires an API key

Spacecraft Crew Certification Act 2049 — the demo rule

Construction All Risks insurance — the adversarial benchmark

Consumer credit prequalification

List every live ruleset

Next steps