# aethis-mcp
MCP server for the Aethis decision engine. Compile legislation, policy, contracts, and regulation into deterministic logic — same input, same answer, every time, with a full audit trail.
[](https://www.npmjs.com/package/aethis-mcp)
[](https://docs.aethis.ai)
[](LICENSE)
[Install](#install) · [Skills](#skills) · [Quick start](#quick-start) · [Tools](#tools) · [Setup](#setup) · [Authoring](#authoring-private-beta) · [DSL](#dsl-capabilities) · [Troubleshooting](#troubleshooting)
---
## 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](https://aethis.ai/developer-access).
**Recommended — one command via [aethis-cli](https://github.com/Aethis-ai/aethis-cli):**
```bash
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:**
```bash
claude mcp add aethis -- npx -y aethis-mcp
```
For Cursor / Claude Desktop / Windsurf manual config, see [Setup](#setup).
> Onboarding an AI coding agent end-to-end? See [docs.aethis.ai/agents/onboarding](https://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`](https://github.com/Aethis-ai/aethis-skills):
```bash
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
})
```
```json
{
"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](https://docs.aethis.ai).
Engine determinism + accuracy benchmarks: [Aethis-ai/confidently-wrong-benchmark](https://github.com/Aethis-ai/confidently-wrong-benchmark).
---
## Tools
35 tools across six groups.
| Group | Access | Tools |
|-------|--------|-------|
| **Decision** | public | `aethis_decide`, `aethis_schema`, `aethis_next_question`, `aethis_explain`, `aethis_explain_failure`, `aethis_graph` |
| **Discovery — public catalogue** | public | `aethis_discover_rulesets` |
| **Discovery — your tenant** | private beta | `aethis_list_projects`, `aethis_list_rulesets`, `aethis_list_rulebooks`, `aethis_rulebook_schema` |
| **Authoring — rulebooks** | private beta | `aethis_create_rulebook`, `aethis_update_rulebook` |
| **Authoring — sections & fields** | private beta | `aethis_discover_sections`, `aethis_refine_sections`, `aethis_validate_sections`, `aethis_set_field_spec`, `aethis_discover_fields`, `aethis_refine_fields`, `aethis_validate_fields` |
| **Authoring — generation** | private beta | `aethis_create_ruleset`, `aethis_set_tests`, `aethis_add_guidance`, `aethis_list_guidance`, `aethis_generate_and_test`, `aethis_generation_status`, `aethis_cancel_generation`, `aethis_refine`, `aethis_publish`, `aethis_add_domain_guidance`, `aethis_list_domain_guidance` |
| **Management** | private beta | `aethis_archive_project`, `aethis_archive_ruleset` |
`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](#authoring-private-beta).
### Prompts
| Prompt | Description |
|--------|-------------|
| `aethis-author` | Step-by-step TDD authoring workflow |
| `aethis-decide` | Decision workflow guide; accepts optional `ruleset_id` |
---
## Setup
Decision tools work with no key. For invited authoring access, run `aethis login`, then install with `aethis mcp install --target `. The installer references a saved profile so the host configuration does not contain the API key.
### Claude Code
```bash
# Decision tools only
claude mcp add aethis -- npx -y aethis-mcp
# With authoring access
claude mcp add aethis -e AETHIS_PROFILE=default -e XDG_CONFIG_HOME=/absolute/path/to/config -- 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):
```json
{
"mcpServers": {
"aethis": {
"command": "npx",
"args": ["-y", "aethis-mcp"]
}
}
}
```
For authoring, add `"env": { "AETHIS_PROFILE": "default", "XDG_CONFIG_HOME": "/absolute/path/to/config" }`. Use your saved profile name and the absolute directory containing `aethis/credentials` (normally your home directory’s `.config`).
### Cursor / Windsurf
Add to `~/.cursor/mcp.json` or `~/.codeium/windsurf/mcp_config.json` (same JSON shape).
### Keys
- `AETHIS_PROFILE` — non-secret saved profile name. It pins the account and endpoint used by this registration, even if the CLI’s `active_profile` later changes.
- `XDG_CONFIG_HOME` — absolute config directory containing `aethis/credentials`. Relative values and credentials symlinks escaping your home/config directory are refused; credential files must have no group/other permission bits (normally `0600`).
- `AETHIS_API_KEY` — optional deliberate process-environment override for the platform key. Prefer saved-profile references when installing; avoid putting raw keys in host config or command arguments. The host must securely supply the process environment; it may not inherit your shell environment.
- `ANTHROPIC_API_KEY` — forwarded per-request to `aethis_generate_and_test`. Used per-call, never stored. See [Passing your Anthropic key safely](#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 `. Mint one key per machine for surgical revocation.
### Credential precedence and restart behavior
MCP parses the CLI credentials file as YAML. `AETHIS_PROFILE` selects a named profile; otherwise the file’s `active_profile` (or `default`) selects it. The profile supplies both its API key and `base_url`, with `https://api.aethis.ai` as the default endpoint. With an explicit `AETHIS_PROFILE`, `AETHIS_API_KEY` and `AETHIS_BASE_URL` deliberately override their respective values. Without an explicit profile selector, `AETHIS_API_KEY` uses `AETHIS_BASE_URL` or the default endpoint, ignoring the implicitly active profile (including implicit anonymous). Missing or malformed explicitly selected profiles fail visibly, including when environment overrides are present. Explicit `AETHIS_PROFILE=anonymous` always stays unsigned. After anonymous setup, run `aethis login` and install again to reference the saved authoring profile, then restart the host.
A saved profile outranks old macOS Keychain entries. If no profile is configured and no explicit name is selected, MCP can use the legacy default keychain entry, then the older flat `credentials.yaml` file. Flat `api_key`/`base_url` files at `aethis/credentials` remain supported. A configured profile awaiting login stays unsigned instead of borrowing another stored key.
The server keeps its authenticated startup key and endpoint paired until restart. If it started without a key, an authenticated tool can pick up a later login for the same endpoint. A changed endpoint causes a visible refusal: restart the MCP host to load the new pair. Startup stderr reports only the credential source, never key values.
### 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.
```jsonc
// claude_desktop_config.json
{
"mcpServers": {
"aethis": {
"command": "npx",
"args": ["aethis-mcp"],
"env": {
"AETHIS_PROFILE": "default",
"XDG_CONFIG_HOME": "/absolute/path/to/config",
"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.
---
## Authoring (private beta)
> Authoring requires an invite. [Request access](https://aethis.ai/developer-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](#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`)
---
## Troubleshooting
| Error | Cause | Fix |
|-------|-------|-----|
| `API key is required` | `AETHIS_API_KEY` not set (authoring) | Configure in MCP client settings, not shell profile |
| `X-Anthropic-Key header is required` | Missing Anthropic key | Pass `anthropic_key_env` (preferred) / `anthropic_key_keychain` / `anthropic_key` on the tool call. See [Passing your Anthropic key safely](#passing-your-anthropic-key-safely). |
| `Ruleset not found` (404) | Wrong ID or archived | `aethis_list_projects` → `aethis_list_rulesets` |
| `Rate limit exceeded` (429) | Daily limit | Client retries automatically. [eng@aethis.ai](mailto:eng@aethis.ai) for higher tier |
| `Cannot publish: tests failing` | Tests don't pass | `aethis_refine` until all tests pass |
| Generation timeout (504) | Server still generating (5–15 min normal) | Wait, then `aethis_list_rulesets({ project_id })` to check. Don't re-trigger |
| `Expected an integer for , got str` | DATE field passed as ISO string | Use `date.toordinal()` integer |
---
## Related
- [aethis-cli](https://github.com/Aethis-ai/aethis-cli) — Python CLI; file-based authoring with YAML test cases
- [aethis-examples](https://github.com/Aethis-ai/aethis-examples) — runnable rulesets (spacecraft, construction-CAR, consumer credit) and benchmark scenarios
- [confidently-wrong-benchmark](https://github.com/Aethis-ai/confidently-wrong-benchmark) — paper, 225-scenario benchmark, LegalBench harness
## Development
```bash
git clone https://github.com/Aethis-ai/aethis-mcp.git
cd aethis-mcp && npm install && npm test && npm run build
```
## License
MIT