---

Install

Authoring is in private beta. Decision tools (aethis_decide, aethis_schema, aethis_explain, aethis_next_question) are public — no key required. Authoring tools (rule generation, test refinement, publishing) require an invite. Request access at aethis.ai/developer-access.

Recommended — one command via aethis-cli:

uv tool install aethis-cli
aethis mcp install --target all

Wires the server into claude-code, cursor, claude-desktop, or windsurf. Idempotent. Restart your editor to pick up the change. Re-run after aethis account generate rotates a key. Full options: aethis mcp install --help.

Manual install:

claude mcp add aethis -- npx -y aethis-mcp

For Cursor / Claude Desktop / Windsurf manual config, see Setup.

Onboarding an AI coding agent end-to-end? See docs.aethis.ai/agents/onboarding — install + verify + auth + workflow patterns in one page.

---

Skills

After the MCP server is installed, add reusable agent workflows with aethis-skills:

npx skills add Aethis-ai/aethis-skills

The skills package provides workflows for policy-to-ruleset authoring, test/refine/publish loops, decisions with trace, and regression comparison. It calls the MCP tools in this package; it does not replace the MCP server.

---

Quick start

aethis_decide({
  ruleset_id: "aethis/spacecraft-crew-certification",
  field_values: { "space.crew.species": "Vogon" },
  include_trace: true
})

{
  "decision": "not_eligible",
  "fields_provided": 1,
  "fields_evaluated": 11,
  "trace": {
    "species_check": "FAIL — species is 'Vogon' (disqualifying, Section 3)"
  }
}

Public rulesets work without a key. Browse: aethis_discover_rulesets({}) or docs.aethis.ai.

Engine determinism + accuracy benchmarks: Aethis-ai/confidently-wrong-benchmark.

---

Tools

30 tools across six groups.

aethis_graph is public for a public showcase ruleset (ruleset_id) and tenant-scoped for a rulebook (rulebook_id) — it returns the ruleset-map graph ({nodes, edges, sections, stats}, each node's display.sentence/display.routes/display.expr) plus a ready-to-render mermaid diagram string. Pass include_graph_overlay: true to aethis_decide to get that same graph back with a specific decision's per-criterion status (satisfied/not_satisfied/pending) stamped onto it (graph_overlay in the response) — a "you are here" map for those inputs.

aethis_create_rulebook / aethis_update_rulebook manage a Rulebook's identity (name/domain/slug/description) and robot_hints — beat-keyed natural-language guidance for the conversational agent. Active beats: general_context, preamble, session_start, postamble, session_end, stuck. Reserved (accepted, not yet acted on): persona, conversational_style, section_transition. Composition (bridging rulesets via outcome_logic) is a separate, larger surface not covered by these two tools yet.

Workflows

Evaluate eligibility (2 calls):

aethis_schema(ruleset_id)          → fields needed
aethis_decide(ruleset_id, fields)  → eligible / not_eligible / undetermined

Pass include_trace: true for the per-criterion evaluation trail. Pass include_explanation: true for human-readable rule descriptions.

aethis_decide accepts either ruleset_id (single ruleset, may be public) or rulebook_id (composed multi-ruleset rulebook) — the two are mutually exclusive. Rulebook decide always requires an API key (AETHIS_API_KEY); anonymous callers get HTTP 401. aethis_graph follows the same ruleset_id/rulebook_id split for the underlying map.

Conversational eligibility (next-question routing):

aethis_next_question(ruleset_id, field_values)

Returns the most informative remaining question and the optimal_path of remaining questions. Call again after each answer; the engine recomputes from the updated state. Stops when a decision is reachable.

Authoring (private beta): see Authoring.

Prompts

---

Setup

Decision tools work with no key. Add AETHIS_API_KEY for authoring access (private beta).

Claude Code

# Decision tools only
claude mcp add aethis -- npx -y aethis-mcp

# With authoring access
claude mcp add aethis -e AETHIS_API_KEY=<your-key> -- npx -y aethis-mcp

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "aethis": {
      "command": "npx",
      "args": ["-y", "aethis-mcp"]
    }
  }
}

For authoring, add "env": { "AETHIS_API_KEY": "<your-key>" }.

Cursor / Windsurf

Add to ~/.cursor/mcp.json or ~/.codeium/windsurf/mcp_config.json (same JSON shape).

Keys

• AETHIS_API_KEY (ak_live_...) — Aethis platform key. Set in the MCP client config, not your shell — the MCP server doesn't inherit shell env. Mint with aethis login or via the dashboard.
• ANTHROPIC_API_KEY — forwarded per-request to aethis_generate_and_test. Used per-call, never stored. See Passing your Anthropic key safely below — prefer the env-var or keychain reference forms over passing the raw key as a tool argument.
• Rotate via aethis account generate + aethis account revoke <key_id>. Mint one key per machine for surgical revocation.

Passing your Anthropic key safely

Authoring tools (aethis_generate_and_test, aethis_refine, aethis_discover_fields, aethis_refine_fields, aethis_discover_sections, aethis_refine_sections) need an Anthropic API key per call. Three accepted forms — listed in preferred order:

1. anthropic_key_env (recommended). Name of an env var (set in the MCP client config) that holds the key. The raw value never appears in the tool call payload, so it does not land in the MCP host's session transcript on disk.

   // claude_desktop_config.json
   {
     "mcpServers": {
       "aethis": {
         "command": "npx",
         "args": ["aethis-mcp"],
         "env": {
           "AETHIS_API_KEY": "ak_live_...",
           "ANTHROPIC_API_KEY": "sk-ant-..."   // never echoed back to the LLM
         }
       }
     }
   }
   

   aethis_generate_and_test({ project_id, anthropic_key_env: "ANTHROPIC_API_KEY" })
   

2. anthropic_key_keychain (macOS). A keychain reference — either "account" (service defaults to aethis-anthropic-key) or "service:account". Store the key once with security add-generic-password -U -s aethis-anthropic-key -a my-anthropic -w 'sk-ant-...', then call:

   aethis_generate_and_test({ project_id, anthropic_key_keychain: "my-anthropic" })
   

3. anthropic_key (deprecated). Pass the raw key as a tool argument. Accepted for backwards compatibility, but the raw value is written verbatim to the host's session transcript JSONL on disk. If a key was ever passed this way, rotate it before relying on the safer forms.

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Authoring (private beta)

Authoring requires an invite. Request access. Decision tools (above) are public.

Three-phase workflow. Phases 1–2 are for multi-section domains; skip them for single-section rules and go straight to Phase 3.

Phase 1 — Section discovery

aethis_discover_sections({ domain, sources: [{ name, content }, ...] })
aethis_validate_sections({ domain, expected_sections, discovered_sections })
aethis_refine_sections({ domain, feedback, sources })

Phase 2 — Field vocabulary

aethis_set_field_spec({
  project_id,
  expected_fields: [{ key, sort, enum_values? }, ...]
})
aethis_discover_fields({ project_id })           // auto-validates against the spec if set
aethis_refine_fields({ project_id, feedback })
aethis_validate_fields({ project_id, expected_fields })

Phase 3 — Generate, test, publish

aethis_create_ruleset({
  name, section_id, domain?, source_text,
  test_cases: [{ name, field_values, expected_outcome }, ...]
})
aethis_generate_and_test({ project_id })
aethis_refine({ project_id, feedback })          // iterate until tests pass
aethis_publish({ project_id })                   // refuses if tests fail; returns ruleset_id on success

If generation polling times out, call aethis_generation_status({ project_id }) before retrying: use its telemetry_availability, server-authoritative worker_lifecycle, and retry_readiness, and retry only when readiness is ready. An old heartbeat alone is not proof that the worker died. Call aethis_cancel_generation({ project_id, job_id, confirm_job_id }) only after showing the observed job_id and receiving explicit confirmation to abandon that active run. It releases the project's job ownership, but worker shutdown may be cooperative rather than immediate; inspect the returned detail. It is a destructive, API-key-protected mutation. The response distinguishes a new cancelled transition from the idempotent already_cancelled result.

Guidance

Targeted hints without regenerating, plus cross-section principles for a domain:

aethis_add_guidance({ project_id, guidance_text, process_type })
aethis_list_guidance({ project_id })

aethis_add_domain_guidance({ domain, guidance_text, process_type, notes? })
aethis_list_domain_guidance({ domain })

process_type is rule_generation (default) or field_extraction.

Diagnose a failing test

aethis_explain_failure({
  ruleset_id, field_values, expected_outcome, test_name
})
// Returns criterion statuses, the failing rule, and a targeted fix hint.

[!IMPORTANT] Tests are the publish gate. aethis_publish refuses to publish a ruleset with a failing test. SMEs write the tests; the LLM generates the rules from source text + guidance; the platform refuses to ship rules that don't satisfy the tests. Better tests = faster convergence.

[!IMPORTANT] Anthropic key required for authoring. Prefer anthropic_key_env (env var name) or anthropic_key_keychain (macOS keychain ref) over the raw anthropic_key argument — see Passing your Anthropic key safely. Used per-request, never stored server-side; the raw form, however, lands in the MCP host's session transcript on disk.

[!IMPORTANT] DATE fields use integer ordinals (date.toordinal()), not ISO strings. 2025-04-13 = 739354. Quick conversion: python3 -c "from datetime import date; print(date(2025,4,13).toordinal())".

---

DSL capabilities

Field types

Type	Description
Bool	True / false
Int	Integer (counts, money as pence, percentages as integers)
Enum	Closed set of named values
Date	Integer ordinal — date.toordinal()
Duration	Integer days
String	Free text — prefer Enum for known sets

Operators

Category	Operators
Logic	AND, OR, NOT, IMPLIES
Comparison	=, ≠, <, ≤, >, ≥
Membership	IN [v1, v2, ...]
Arithmetic	+, − for Int/Date; * for Int
Aggregation	min(...), max(...)

Helpers

• days_between(date_a, date_b) → Int
• years_between(date_a, date_b) → Int — completed whole years between the two dates (leap-correct). Use this for age from a date-of-birth field; never derive age as days_between(...) / 365.
• min(a, b, ...), max(a, b, ...) → Int
• Constant arithmetic folded at authoring time (5 * 365 → 1825)

Not supported

• Division between runtime field values
• Weighted scoring or probabilistic outcomes
• Lists as field values (use pre-aggregated Int / Bool)
• More than 3 outcome tiers (eligible / not_eligible / undetermined)

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Troubleshooting

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Related

• aethis-cli — Python CLI; file-based authoring with YAML test cases
• aethis-examples — runnable rulesets (spacecraft, construction-CAR, consumer credit) and benchmark scenarios
• confidently-wrong-benchmark — paper, 225-scenario benchmark, LegalBench harness

Development

git clone https://github.com/Aethis-ai/aethis-mcp.git
cd aethis-mcp && npm install && npm test && npm run build

License

MIT