cardano-protocol-params

Files (4)

• SKILL.md
• docker-fallback.md · reference/
• pparams.md · reference/
• cardano-cli.sh · scripts/

SKILL.md (first lines)

# cardano-protocol-params

## When to use
- Fetching fresh protocol parameters
- Understanding fee calculation inputs
- Debugging min-UTxO or execution budget issues
- Comparing params across networks

## Operating rules (must follow)
- Always fetch fresh params for the target network
- Never assume mainnet params apply to testnets
- Keep pparams.json with tx artifacts for reproducibility

## Docker fallback mode
If `cardano-cli` is not installed locally, use the wrapper script in this skill folder to run **cardano-cli inside Docker** (the Cardano node container images include the CLI).

```bash
chmod +x {baseDir}/scripts/cardano-cli.sh
{baseDir}/scripts/cardano-cli.sh version
```

Notes:
- The wrapper mounts your current directory into the container as `/work` so files like `pparams.json`, `tx.body`, `datum.json` work normally.
- If you have a local node socket, set `CARDANO_NODE_SOCKET_PATH` before running so `query` commands work.
- Override the image with `CARDANO_DOCKER_IMAGE=ghcr.io/intersectmbo/cardano-node:<tag>`.

## Key parameters explained

### Fee calculation
```
minFeeA: 44           # lovelace per byte
minFeeB: 155381       # base fee in lovelace
```
Formula: `fee = minFeeA * txSize + minFeeB`

### Min UTxO
```
coinsPerUTxOByte: 4310   # lovelace per byte of UTxO
```
Minimum ADA required = size of UTxO (including datum) × coinsPerUTxOByte

### Execution units (Plutus)
```
maxTxExecutionUnits:
  steps: 10000000000     # CPU budget
  memory: 10000000       # Memory budget
executionUnitPrices:
  priceSteps: 0.0000721  # lovelace per step
  priceMemory: 0.0577    # lovelace per memory unit
```

### Reference scripts
```
minFeeRefScriptCostPerByte: 15  # Cost for using reference scripts
```

## Workflow

### Fetch parameters
```bash
# Preprod
cardano-cli conway query protocol-parameters \
  --testnet-magic 1 \
  --out-file pparams-preprod.json

# Mainnet
cardano-cli conway query protocol-parameters \
  --mainnet \
  --out-file pparams-mainnet.json
```

### Extract key values
```bash
# Using jq
cat pparams.json | jq '{
  minFeeA: .txFeePerByte,
  minFeeB: .txFeeFixed,
  coinsPerUTxOByte: .utxoCostPerByte,
  maxTxSize: .maxTxSize,
  maxValSize: .maxValueSize
}'
```

### Calculate min-UTxO for output
```bash
# Approximate: base ~160 bytes + datum size
# For simple ADA-only output: ~1 ADA minimum
# For output with tokens: varies by token count/names
```

## Examples

### Example: Debug "UTxO too small" error
**Problem:** Transaction fails with min-UTxO error

**Response:**
```bash
# 1. Fetch current params
cardano-cli conway query protocol-parameters \
  --testnet-magic 1 \
  --out-file pparams.json

# 2. Check coinsPerUTxOByte
cat pparams.json | jq .utxoCostPerByte
# Result: 4310

# 3. Estimate min-UTxO for your output
# Simple ADA output: ~160 bytes × 4310 = ~690,000 lovelace
# With inline datum: add datum size × 4310
# With tokens: add ~30 bytes per token

# 4. Solution: increase output amount above minimum
```

### Example: Estimate script execution cost
**Problem:** Need to budget for Plutus script

**Response:**
```bash

From Flux-Point-Studios/cardano-agent-skills, MIT.

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