> ## Documentation Index
> Fetch the complete documentation index at: https://mwillaimission.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Capability Ontology: Shared Agent Service Taxonomy

> A structured vocabulary for declaring and discovering agent services across five root domains — travel, finance, health, commerce, and productivity.

AgentLedger's capability ontology is the shared vocabulary that makes agent discovery possible. When you register a service, you declare its capabilities using this taxonomy. When an agent searches for a service, it queries against the same vocabulary. The entity that controls this vocabulary controls discovery across every registry that adopts it — which is why the ontology is the most strategically important artifact AgentLedger publishes.

## Design rules

The ontology follows five structural rules that enforce clarity and prevent ambiguity:

1. Root categories are **DOMAINS** — what world does this capability touch?
2. L2 categories are **FUNCTIONS** — what class of action does this perform?
3. L3 tags are **CAPABILITIES** — what specific thing can your service do?
4. Every capability must be a **verb phrase** — agents operate in actions, not categories.
5. No capability appears in two branches — this forces precision in how you declare what your service does.

<Info>
  These rules mean you cannot claim a capability just because your service is adjacent to it. If your service books flights, you declare `travel.air.book` — not `travel.air` or a custom tag you invented.
</Info>

## The taxonomy tree

The current ontology covers five root domains with 20 L2 function branches and 65 L3 capability tags. Use the exact dot-notation strings below when you populate the `capabilities` field in your Agent Manifest.

```text theme={null}
ROOT
├── TRAVEL
│   ├── travel.air
│   │   ├── travel.air.search
│   │   ├── travel.air.book
│   │   ├── travel.air.cancel
│   │   └── travel.air.track
│   ├── travel.ground
│   │   ├── travel.ground.rail
│   │   ├── travel.ground.car_rental
│   │   └── travel.ground.rideshare
│   ├── travel.lodging
│   │   ├── travel.lodging.search
│   │   ├── travel.lodging.book
│   │   └── travel.lodging.cancel
│   └── travel.documents
│       ├── travel.documents.visa
│       └── travel.documents.passport
│
├── FINANCE
│   ├── finance.payments
│   │   ├── finance.payments.send
│   │   ├── finance.payments.request
│   │   └── finance.payments.verify
│   ├── finance.accounts
│   │   ├── finance.accounts.balance
│   │   ├── finance.accounts.history
│   │   └── finance.accounts.open
│   ├── finance.investment
│   │   ├── finance.investment.quote
│   │   ├── finance.investment.trade
│   │   └── finance.investment.analyze
│   └── finance.insurance
│       ├── finance.insurance.quote
│       └── finance.insurance.claim
│
├── HEALTH
│   ├── health.appointments
│   │   ├── health.appointments.book
│   │   ├── health.appointments.cancel
│   │   └── health.appointments.remind
│   ├── health.records
│   │   ├── health.records.retrieve
│   │   ├── health.records.share
│   │   └── health.records.summarize
│   ├── health.pharmacy
│   │   ├── health.pharmacy.refill
│   │   ├── health.pharmacy.check
│   │   └── health.pharmacy.locate
│   └── health.monitoring
│       ├── health.monitoring.vitals
│       └── health.monitoring.alert
│
├── COMMERCE
│   ├── commerce.shopping
│   │   ├── commerce.shopping.search
│   │   ├── commerce.shopping.compare
│   │   ├── commerce.shopping.purchase
│   │   └── commerce.shopping.return
│   ├── commerce.subscriptions
│   │   ├── commerce.subscriptions.create
│   │   ├── commerce.subscriptions.cancel
│   │   └── commerce.subscriptions.modify
│   ├── commerce.delivery
│   │   ├── commerce.delivery.track
│   │   ├── commerce.delivery.schedule
│   │   └── commerce.delivery.redirect
│   └── commerce.reviews
│       ├── commerce.reviews.retrieve
│       └── commerce.reviews.analyze
│
└── PRODUCTIVITY
    ├── productivity.calendar
    │   ├── productivity.calendar.read
    │   ├── productivity.calendar.create
    │   ├── productivity.calendar.schedule
    │   └── productivity.calendar.cancel
    ├── productivity.communication
    │   ├── productivity.communication.email_send
    │   ├── productivity.communication.email_read
    │   ├── productivity.communication.sms
    │   └── productivity.communication.notify
    ├── productivity.documents
    │   ├── productivity.documents.create
    │   ├── productivity.documents.retrieve
    │   ├── productivity.documents.sign
    │   └── productivity.documents.summarize
    └── productivity.automation
        ├── productivity.automation.trigger
        ├── productivity.automation.monitor
        └── productivity.automation.report
```

## Why these five roots?

These domains map to where autonomous agents will first replace human action — and where the liability stakes are highest. They are also almost entirely uncovered by MCP's current adoption, which skews heavily toward developer tooling.

| MCP coverage            | AgentLedger coverage    |
| ----------------------- | ----------------------- |
| Database connectors     | Travel                  |
| GitHub / CI-CD          | Finance                 |
| Communication platforms | Health                  |
| Cloud infrastructure    | Commerce + Productivity |

<Tip>
  If your service operates in a domain not yet covered by the ontology — legal, government, real estate — hold on: v0.2 adds those roots. In the meantime, open an issue on GitHub to flag your use case and influence the expansion.
</Tip>

## Version roadmap

The ontology is versioned independently of the AgentLedger registry. You can pin your manifest to a specific ontology version.

| Version            | Scope                                                                    |
| ------------------ | ------------------------------------------------------------------------ |
| **v0.1** (current) | 5 roots, 20 L2 branches, 65 L3 capabilities                              |
| v0.2               | Add `LEGAL`, `GOVERNMENT`, `REAL_ESTATE` roots                           |
| v0.3               | Add L4 sub-capability parameters + input/output schemas                  |
| v1.0               | Full semantic embeddings trained on ontology + real service descriptions |

<Note>
  The ontology is an open standard. Propose changes, flag gaps, or request new branches by opening an issue on [GitHub](https://github.com/mwill20/AgentLedger).
</Note>