# VRS v2 Quickstart

## Installation

```bash
pip install "ai4gh[vrs]"
```

## Compute VRS Identifiers

```python
from ai4gh.specs.vrs.models import Allele, SequenceLocation, SequenceReference

# Create a VRS Allele
allele = Allele(
    location=SequenceLocation(
        sequenceReference=SequenceReference(
            refgetAccession="SQ.abc123",
        ),
        start=100,
        end=101,
    ),
    state={"type": "LiteralSequenceExpression", "sequence": "T"},
)

# Compute the VRS identifier
print(f"Allele: {allele.model_dump_json(indent=2)}")
```

## MCP Tool

```json
{
  "tool": "vrs_compute_id",
  "arguments": {
    "variation_json": "{\"type\": \"Allele\", \"location\": {\"type\": \"SequenceLocation\", \"sequenceReference\": {\"refgetAccession\": \"SQ.abc123\"}, \"start\": 100, \"end\": 101}, \"state\": {\"type\": \"LiteralSequenceExpression\", \"sequence\": \"T\"}}"
  }
}
```

## Data Models

### Core VRS

```python
from ai4gh.specs.vrs.models import (
    Allele,
    CopyNumberChange,
    CopyNumberCount,
    SequenceLocation,
    SequenceReference,
)
```

### Cat-VRS (Categorical Variants)

```python
from ai4gh.specs.cat_vrs.models import (
    CategoricalVariant,
    CanonicalAllele,
    DescribedVariation,
)
```

### VA-Spec (Variant Annotation)

```python
from ai4gh.specs.va_spec.models import (
    VariantClassification,
    VariantPathogenicity,
    VariantTherapeuticResponse,
)
```
