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Overview

Decodes revert reasons from failed Cronos transactions and provides human-readable explanations. Tool Name: decode_transaction_error

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Parameters

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tx_hash
string
required
Transaction hash (0x… with 64 hex characters)
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chain
enum
default:"evm"
Chain to queryOptions: "evm", "zkEvm"

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Response

{
  "transaction": {
    "hash": "0xabc123...",
    "chain": "Cronos EVM",
    "status": "FAILED",
    "from": "0x123...",
    "to": "0x456...",
    "protocol": "VVS Finance (DEX)",
    "timestamp": "2026-01-23T03:11:54.000Z",
    "block_number": 12345678
  },
  "error": {
    "type": "STANDARD_ERROR",
    "signature": "0x08c379a0",
    "name": "Error",
    "raw_message": "0x08c379a0...",
    "decoded_message": "Insufficient output amount",
    "explanation": "The swap would result in less tokens than your slippage tolerance allows",
    "suggested_fix": "Increase your slippage tolerance or split the trade into smaller amounts",
    "protocol_docs": "https://docs.vvs.finance/trading"
  },
  "gas_analysis": {
    "gas_used": 150000,
    "gas_limit": 200000,
    "gas_price_gwei": "5000.00",
    "wasted_cro": "0.750000",
    "utilization_percent": 75.0
  },
  "context": {
    "method": "swapExactTokensForTokens",
    "input_data_length": 196,
    "value_cro": "0.000000"
  }
}

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Supported Error Types

Error(string) - Standard Solidity error with decoded messageCommon causes:
  • Insufficient balance
  • Slippage exceeded
  • Unauthorized access
  • Invalid parameters

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Example Usage

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Python (MCP Client)

result = use_mcp_tool(
    server_name="cato",
    tool_name="decode_transaction_error",
    arguments={
        "tx_hash": "0xabc123...",
        "chain": "evm"
    }
)

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Natural Language Query

"Why did this transaction fail: 0xabc123..."

"Decode the error for transaction 0xdef456... on zkEVM"

"What went wrong with my swap transaction?"

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Response Fields

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Transaction Object

FieldTypeDescription
hashstringTransaction hash
chainstringChain name
statusstringTransaction status
fromstringSender address
tostringRecipient address
protocolstringDetected protocol
timestampstringTransaction timestamp
block_numbernumberBlock number

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Error Object

FieldTypeDescription
typestringError type
signaturestringError signature
namestringError name
raw_messagestringRaw error data
decoded_messagestringHuman-readable message
explanationstringPlain English explanation
suggested_fixstringHow to fix the issue
protocol_docsstringRelevant documentation

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Gas Analysis Object

FieldTypeDescription
gas_usednumberGas consumed
gas_limitnumberGas limit set
gas_price_gweistringGas price in Gwei
wasted_crostringCRO wasted on failed tx
utilization_percentnumberGas utilization %

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Common Errors & Solutions

Cause: Slippage tolerance too low for market conditionsSolution:
  • Increase slippage tolerance in DEX settings
  • Split large trades into smaller amounts
  • Wait for better market conditions
Cause: Trying to send more tokens than you haveSolution:
  • Check token balance
  • Account for existing approvals
  • Verify token decimals
Cause: Contract not approved to spend tokensSolution:
  • Call approve() on token contract
  • Set allowance to desired amount
  • Use max approval for convenience
Cause: Gas limit set too lowSolution:
  • Increase gas limit by 20-30%
  • Use gas estimation tools
  • Check for infinite loops in contract
Cause: Gas price below network minimumSolution:
  • Use current network gas price
  • Check gas price oracle
  • Wait for lower network congestion

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Gas Analysis Features

Cost Calculation

Calculate exact CRO wasted on failed transaction

Utilization %

See how much of gas limit was used

Price Tracking

Record gas price at transaction time

Optimization Tips

Get suggestions for better gas usage

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Protocol Detection

The tool automatically identifies the protocol you’re interacting with:
  • Tectonic - Lending protocol
  • VVS Finance - DEX
  • Fulcrom - Perpetuals
  • Token Contracts - ERC-20 transfers
  • NFT Contracts - ERC-721/1155
  • Custom Contracts - Generic smart contracts
Protocol-specific errors include links to relevant documentation for troubleshooting.

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Use Cases

Debug smart contract interactions during development and testing.

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Error Handling

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Transaction Not Found

{
  "content": [
    {
      "type": "text",
      "text": "{\"error\": \"Transaction not found\"}"
    }
  ],
  "isError": true
}
Solution: Verify transaction hash and chain parameter

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RPC Timeout

If RPC times out (>5s), you’ll receive a timeout error with retry suggestion.

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Best Practices

1

Check Transaction Status

Always verify the transaction failed before decoding
2

Select Correct Chain

Ensure you’re querying the right chain (EVM vs zkEVM)
3

Review Gas Analysis

Check if out-of-gas was the issue before diving into error details
4

Follow Suggested Fixes

Apply the suggested fixes before retrying
5

Consult Documentation

Review protocol documentation links for complex errors

query_cronos_sdk_docs

Find code examples for proper implementation

Transaction History

View all transactions for an address