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Cryo MCP 🧊

A Model Completion Protocol (MCP) server for the Cryo blockchain data extraction tool.

Cryo MCP allows you to access Cryo's powerful blockchain data extraction capabilities via an API server that implements the MCP protocol, making it easy to query blockchain data from any MCP-compatible client.

For LLM Users: SQL Query Workflow Guide

When using this MCP server to run SQL queries on blockchain data, follow this workflow:

  1. Download data with query_dataset:

    result = query_dataset(
        dataset="blocks",  # or "transactions", "logs", etc.
        blocks="15000000:15001000",  # or use blocks_from_latest=100
        output_format="parquet"  # important: use parquet for SQL
    )
    files = result.get("files", [])  # Get the returned file paths
  2. Explore schema with get_sql_table_schema:

    # Check what columns are available in the file
    schema = get_sql_table_schema(files[0])
    # Now you can see all columns, data types, and sample data
  3. Run SQL with query_sql:

    # Option 1: Simple table reference (DuckDB will match the table name to file)
    sql_result = query_sql(
        query="SELECT block_number, timestamp, gas_used FROM blocks",
        files=files  # Pass the files from step 1
    )
    
    # Option 2: Using read_parquet() with explicit file path
    sql_result = query_sql(
        query=f"SELECT block_number, timestamp, gas_used FROM read_parquet('{files[0]}')",
        files=files  # Pass the files from step 1
    )

Alternatively, use the combined approach with query_blockchain_sql:

# Option 1: Simple table reference
result = query_blockchain_sql(
    sql_query="SELECT * FROM blocks",
    dataset="blocks",
    blocks_from_latest=100
)

# Option 2: Using read_parquet()
result = query_blockchain_sql(
    sql_query="SELECT * FROM read_parquet('/path/to/file.parquet')",  # Path doesn't matter
    dataset="blocks",
    blocks_from_latest=100
)

For a complete working example, see examples/sql_workflow_example.py.

Related MCP server: EVM MCP Server

Features

  • Full Cryo Dataset Access: Query any Cryo dataset through an API server

  • MCP Integration: Works seamlessly with MCP clients

  • Flexible Query Options: Support for all major Cryo filtering and output options

  • Block Range Options: Query specific blocks, latest block, or relative ranges

  • Contract Filtering: Filter data by contract address

  • Latest Block Access: Easy access to the latest Ethereum block data

  • Multiple Output Formats: JSON, CSV, and Parquet support

  • Schema Information: Get detailed dataset schemas and sample data

  • SQL Queries: Run SQL queries directly against downloaded blockchain data

Installation (Optional)

This is not required if you will run the tool with uvx directly.

# install with UV (recommended)
uv tool install cryo-mcp

Requirements

  • Python 3.8+

  • uv

  • A working installation of Cryo

  • Access to an Ethereum RPC endpoint

  • DuckDB (for SQL query functionality)

Quick Start

Usage with Claude Code

  1. Run claude mcp add for an interactive prompt.

  2. Enter uvx as the command to run.

  3. Enter cryo-mcp --rpc-url <ETH_RPC_URL> [--data-dir <DATA_DIR>] as the args

  4. Alternatively, provide ETH_RPC_URL and CRYO_DATA_DIR as environment variables instead.

New instances of claude will now have access to cryo as configured to hit your RPC endpoint and store data in the specified directory.

Available Tools

Cryo MCP exposes the following MCP tools:

list_datasets()

Returns a list of all available Cryo datasets.

Example:

client.list_datasets()

query_dataset()

Query a Cryo dataset with various filtering options.

Parameters:

  • dataset (str): The name of the dataset to query (e.g., 'blocks', 'transactions', 'logs')

  • blocks (str, optional): Block range specification (e.g., '1000:1010')

  • start_block (int, optional): Start block number (alternative to blocks)

  • end_block (int, optional): End block number (alternative to blocks)

  • use_latest (bool, optional): If True, query the latest block

  • blocks_from_latest (int, optional): Number of blocks from latest to include

  • contract (str, optional): Contract address to filter by

  • output_format (str, optional): Output format ('json', 'csv', 'parquet')

  • include_columns (list, optional): Columns to include alongside defaults

  • exclude_columns (list, optional): Columns to exclude from defaults

Example:

# Get transactions from blocks 15M to 15.01M
client.query_dataset('transactions', blocks='15M:15.01M')

# Get logs for a specific contract from the latest 100 blocks
client.query_dataset('logs', blocks_from_latest=100, contract='0x1234...')

# Get just the latest block
client.query_dataset('blocks', use_latest=True)

lookup_dataset()

Get detailed information about a specific dataset, including schema and sample data.

Parameters:

  • name (str): The name of the dataset to look up

  • sample_start_block (int, optional): Start block for sample data

  • sample_end_block (int, optional): End block for sample data

  • use_latest_sample (bool, optional): Use latest block for sample

  • sample_blocks_from_latest (int, optional): Number of blocks from latest for sample

Example:

client.lookup_dataset('logs')

get_latest_ethereum_block()

Returns information about the latest Ethereum block.

Example:

client.get_latest_ethereum_block()

SQL Query Tools

Cryo MCP includes several tools for running SQL queries against blockchain data:

query_sql()

Run a SQL query against downloaded blockchain data.

Parameters:

  • query (str): SQL query to execute

  • files (list, optional): List of parquet file paths to query. If None, will use all files in the data directory.

  • include_schema (bool, optional): Whether to include schema information in the result

Example:

# Run against all available files
client.query_sql("SELECT * FROM read_parquet('/path/to/blocks.parquet') LIMIT 10")

# Run against specific files
client.query_sql(
    "SELECT * FROM read_parquet('/path/to/blocks.parquet') LIMIT 10",
    files=['/path/to/blocks.parquet']
)

query_blockchain_sql()

Query blockchain data using SQL, automatically downloading any required data.

Parameters:

  • sql_query (str): SQL query to execute

  • dataset (str, optional): The dataset to query (e.g., 'blocks', 'transactions')

  • blocks (str, optional): Block range specification

  • start_block (int, optional): Start block number

  • end_block (int, optional): End block number

  • use_latest (bool, optional): If True, query the latest block

  • blocks_from_latest (int, optional): Number of blocks before the latest to include

  • contract (str, optional): Contract address to filter by

  • force_refresh (bool, optional): Force download of new data even if it exists

  • include_schema (bool, optional): Include schema information in the result

Example:

# Automatically downloads blocks data if needed, then runs the SQL query
client.query_blockchain_sql(
    sql_query="SELECT block_number, gas_used, timestamp FROM blocks ORDER BY gas_used DESC LIMIT 10",
    dataset="blocks",
    blocks_from_latest=100
)

list_available_sql_tables()

List all available tables that can be queried with SQL.

Example:

client.list_available_sql_tables()

get_sql_table_schema()

Get the schema for a specific parquet file.

Parameters:

  • file_path (str): Path to the parquet file

Example:

client.get_sql_table_schema("/path/to/blocks.parquet")

get_sql_examples()

Get example SQL queries for different blockchain datasets.

Example:

client.get_sql_examples()

Configuration Options

When starting the Cryo MCP server, you can use these command-line options:

  • --rpc-url URL: Ethereum RPC URL (overrides ETH_RPC_URL environment variable)

  • --data-dir PATH: Directory to store downloaded data (overrides CRYO_DATA_DIR environment variable, defaults to ~/.cryo-mcp/data/)

Environment Variables

  • ETH_RPC_URL: Default Ethereum RPC URL to use when not specified via command line

  • CRYO_DATA_DIR: Default directory to store downloaded data when not specified via command line

Advanced Usage

SQL Queries Against Blockchain Data

Cryo MCP allows you to run powerful SQL queries against blockchain data, combining the flexibility of SQL with Cryo's data extraction capabilities:

Two-Step SQL Query Flow

You can split data extraction and querying into two separate steps:

# Step 1: Download data and get file paths
download_result = client.query_dataset(
    dataset="transactions",
    blocks_from_latest=1000,
    output_format="parquet"
)

# Step 2: Use the file paths to run SQL queries
file_paths = download_result.get("files", [])
client.query_sql(
    query=f"""
    SELECT 
        to_address as contract_address, 
        COUNT(*) as tx_count,
        SUM(gas_used) as total_gas,
        AVG(gas_used) as avg_gas
    FROM read_parquet('{file_paths[0]}')
    WHERE to_address IS NOT NULL
    GROUP BY to_address
    ORDER BY total_gas DESC
    LIMIT 20
    """,
    files=file_paths
)

Combined SQL Query Flow

For convenience, you can also use the combined function that handles both steps:

# Get top gas-consuming contracts
client.query_blockchain_sql(
    sql_query="""
    SELECT 
        to_address as contract_address, 
        COUNT(*) as tx_count,
        SUM(gas_used) as total_gas,
        AVG(gas_used) as avg_gas
    FROM read_parquet('/path/to/transactions.parquet')
    WHERE to_address IS NOT NULL
    GROUP BY to_address
    ORDER BY total_gas DESC
    LIMIT 20
    """,
    dataset="transactions",
    blocks_from_latest=1000
)

# Find blocks with the most transactions
client.query_blockchain_sql(
    sql_query="""
    SELECT 
        block_number, 
        COUNT(*) as tx_count
    FROM read_parquet('/path/to/transactions.parquet')
    GROUP BY block_number
    ORDER BY tx_count DESC
    LIMIT 10
    """,
    dataset="transactions",
    blocks="15M:16M"
)

# Analyze event logs by topic
client.query_blockchain_sql(
    sql_query="""
    SELECT 
        topic0, 
        COUNT(*) as event_count
    FROM read_parquet('/path/to/logs.parquet')
    GROUP BY topic0
    ORDER BY event_count DESC
    LIMIT 20
    """,
    dataset="logs",
    blocks_from_latest=100
)

Note: For SQL queries, always use output_format="parquet" when downloading data to ensure optimal performance with DuckDB. When using query_blockchain_sql, you should refer to the file paths directly in your SQL using the read_parquet() function.

Querying with Block Ranges

Cryo MCP supports the full range of Cryo's block specification syntax:

# Using block numbers
client.query_dataset('transactions', blocks='15000000:15001000')

# Using K/M notation
client.query_dataset('logs', blocks='15M:15.01M')

# Using offsets from latest 
client.query_dataset('blocks', blocks_from_latest=100)

Contract Filtering

Filter logs and other data by contract address:

# Get all logs for USDC contract
client.query_dataset('logs', 
                    blocks='16M:16.1M', 
                    contract='0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48')

Column Selection

Include only the columns you need:

# Get just block numbers and timestamps
client.query_dataset('blocks', 
                    blocks='16M:16.1M', 
                    include_columns=['number', 'timestamp'])

Development

Project Structure

cryo-mcp/
ā”œā”€ā”€ cryo_mcp/           # Main package directory
│   ā”œā”€ā”€ __init__.py     # Package initialization
│   ā”œā”€ā”€ server.py       # Main MCP server implementation
│   ā”œā”€ā”€ sql.py          # SQL query functionality
ā”œā”€ā”€ tests/              # Test directory
│   ā”œā”€ā”€ test_*.py       # Test files
ā”œā”€ā”€ pyproject.toml      # Project configuration
ā”œā”€ā”€ README.md           # Project documentation

Run Tests

uv run pytest

License

MIT

Credits

  • Built on top of the amazing Cryo tool by Paradigm

  • Uses the MCP protocol for API communication

Available Tools

10 tools
get_latest_ethereum_blockB
Get information about the latest Ethereum block

Returns:
    Information about the latest block including block number

Inputs: no named parameters.

get_sql_examplesA
Get example SQL queries for different blockchain datasets with DuckDB

SQL WORKFLOW TIPS:
1. First download data: result = query_dataset('dataset_name', blocks='...', output_format='parquet')
2. Inspect schema: schema = get_sql_table_schema(result['files'][0])
3. Run SQL: query_sql("SELECT * FROM read_parquet('/path/to/file.parquet')", files=result['files'])

OR use the combined approach:
- query_blockchain_sql(sql_query="SELECT * FROM read_parquet('...')", dataset='blocks', blocks='...')

Returns:
    Dictionary of example queries categorized by dataset type and workflow patterns

Inputs: no named parameters.

get_sql_table_schemaA
Get the schema and sample data for a specific parquet file

WORKFLOW NOTE: Use this function to explore the structure of parquet files
before writing SQL queries against them. This will show you:
1. All available columns and their data types
2. Sample data from the file
3. Total row count

Usage example:
1. Get list of files: files = list_available_sql_tables()
2. For a specific file: schema = get_sql_table_schema(files[0]['path'])
3. Use columns in your SQL: query_sql("SELECT column1, column2 FROM read_parquet('/path/to/file.parquet')")

Args:
    file_path: Path to the parquet file (from list_available_sql_tables or query_dataset)
    
Returns:
    Table schema information including columns, data types, and sample data

Inputs: file_path (required).

get_transaction_by_hashC
Get detailed information about a transaction by its hash

Args:
    tx_hash: The transaction hash to look up
    
Returns:
    Detailed information about the transaction

Inputs: tx_hash (required).

list_available_sql_tablesA
List all available parquet files that can be queried with SQL

USAGE NOTES:
- This function lists parquet files that have already been downloaded
- Each file can be queried using read_parquet('/path/to/file.parquet') in your SQL
- For each file, this returns the file path, dataset type, and other metadata
- Use these file paths in your SQL queries with query_sql()

Returns:
    List of available files and their metadata

Inputs: no named parameters.

list_datasetsB

Return a list of all available cryo datasets

Inputs: no named parameters.

lookup_datasetA
Look up a specific dataset and return detailed information about it. IMPORTANT: Always use this
function before querying a new dataset to understand its required parameters and schema.

The returned information includes:
1. Required parameters for the dataset (IMPORTANT for datasets like 'balances' that need an address)
2. Schema details showing available columns and data types
3. Example queries for the dataset

When the dataset requires specific parameters like 'address' (for 'balances'),
ALWAYS use the 'contract' parameter in query_dataset() to pass these values.

Example:
For 'balances' dataset, lookup_dataset('balances') will show it requires an 'address' parameter.
You should then query it using:
query_dataset('balances', blocks='1000:1010', contract='0x1234...')

Args:
    name: The name of the dataset to look up
    sample_start_block: Optional start block for sample data (integer)
    sample_end_block: Optional end block for sample data (integer)
    use_latest_sample: If True, use the latest block for sample data
    sample_blocks_from_latest: Number of blocks before the latest to include in sample
    
Returns:
    Detailed information about the dataset including schema and available fields

Inputs: name (required), sample_blocks_from_latest, sample_end_block, sample_start_block, +1 more.

query_blockchain_sqlA
Download blockchain data and run SQL query in a single step

CONVENIENCE FUNCTION: This combines query_dataset and query_sql into one call.

You can write SQL queries using either approach:
1. Simple table references: "SELECT * FROM blocks LIMIT 10"
2. Explicit read_parquet: "SELECT * FROM read_parquet('/path/to/file.parquet') LIMIT 10"

DATASET-SPECIFIC PARAMETERS:
For datasets that require specific address parameters (like 'balances', 'erc20_transfers', etc.),
ALWAYS use the 'contract' parameter to pass ANY Ethereum address. For example:

- For 'balances' dataset: Use contract parameter for the address you want balances for
  query_blockchain_sql(
      sql_query="SELECT * FROM balances",
      dataset="balances",
      blocks='1000:1010',
      contract='0x123...'  # Address you want balances for
  )

Examples:
```
# Using simple table name
query_blockchain_sql(
    sql_query="SELECT * FROM blocks LIMIT 10",
    dataset="blocks",
    blocks_from_latest=100
)

# Using read_parquet() (the path will be automatically replaced)
query_blockchain_sql(
    sql_query="SELECT * FROM read_parquet('/any/path.parquet') LIMIT 10",
    dataset="blocks",
    blocks_from_latest=100
)
```

ALTERNATIVE WORKFLOW (more control):
If you need more control, you can separate the steps:
1. Download data: result = query_dataset('blocks', blocks_from_latest=100, output_format='parquet')
2. Inspect schema: schema = get_sql_table_schema(result['files'][0])
3. Run SQL query: query_sql("SELECT * FROM blocks", files=result['files'])

Args:
    sql_query: SQL query to execute - using table names or read_parquet()
    dataset: The specific dataset to query (e.g., 'transactions', 'logs', 'balances')
             If None, will be extracted from the SQL query
    blocks: Block range specification as a string (e.g., '1000:1010')
    start_block: Start block number (alternative to blocks)
    end_block: End block number (alternative to blocks)
    use_latest: If True, query the latest block
    blocks_from_latest: Number of blocks before the latest to include
    contract: Contract address to filter by - IMPORTANT: Use this parameter for ALL address-based filtering
      regardless of the parameter name in the native cryo command (address, contract, etc.)
    force_refresh: Force download of new data even if it exists
    include_schema: Include schema information in the result
    
Returns:
    SQL query results and metadata

Inputs: sql_query (required), blocks, blocks_from_latest, contract, +6 more.

query_datasetA
Download blockchain data and return the file paths where the data is stored.

IMPORTANT WORKFLOW NOTE: When running SQL queries, use this function first to download
data, then use the returned file paths with query_sql() to execute SQL on those files.

Example workflow for SQL:
1. First download data: result = query_dataset('transactions', blocks='1000:1010', output_format='parquet')
2. Get file paths: files = result.get('files', [])
3. Run SQL query: query_sql("SELECT * FROM read_parquet('/path/to/file.parquet')", files=files)

DATASET-SPECIFIC PARAMETERS:
For datasets that require specific address parameters (like 'balances', 'erc20_transfers', etc.),
ALWAYS use the 'contract' parameter to pass ANY Ethereum address. For example:

- For 'balances' dataset: Use contract parameter for the address you want balances for
  query_dataset('balances', blocks='1000:1010', contract='0x123...')

- For 'logs' or 'erc20_transfers': Use contract parameter for contract address
  query_dataset('logs', blocks='1000:1010', contract='0x123...')

To check what parameters a dataset requires, always use lookup_dataset() first:
lookup_dataset('balances')  # Will show required parameters

Args:
    dataset: The name of the dataset to query (e.g., 'logs', 'transactions', 'balances')
    blocks: Block range specification as a string (e.g., '1000:1010')
    start_block: Start block number as integer (alternative to blocks)
    end_block: End block number as integer (alternative to blocks)
    use_latest: If True, query the latest block
    blocks_from_latest: Number of blocks before the latest to include (e.g., 10 = latest-10 to latest)
    contract: Contract address to filter by - IMPORTANT: Use this parameter for ALL address-based filtering
      regardless of the parameter name in the native cryo command (address, contract, etc.)
    output_format: Output format (json, csv, parquet) - use 'parquet' for SQL queries
    include_columns: Columns to include alongside the defaults
    exclude_columns: Columns to exclude from the defaults

Returns:
    Dictionary containing file paths where the downloaded data is stored

Inputs: dataset (required), blocks, blocks_from_latest, contract, +6 more.

query_sqlA
Run a SQL query against downloaded blockchain data files

IMPORTANT WORKFLOW: This function should be used after calling query_dataset
to download data. Use the file paths returned by query_dataset as input to this function.

Workflow steps:
1. Download data: result = query_dataset('transactions', blocks='1000:1010', output_format='parquet')
2. Get file paths: files = result.get('files', [])
3. Execute SQL using either:
   - Direct table references: query_sql("SELECT * FROM transactions", files=files)
   - Or read_parquet(): query_sql("SELECT * FROM read_parquet('/path/to/file.parquet')", files=files)

To see the schema of a file, use get_sql_table_schema(file_path) before writing your query.

DuckDB supports both approaches:
1. Direct table references (simpler): "SELECT * FROM blocks"
2. read_parquet function (explicit): "SELECT * FROM read_parquet('/path/to/file.parquet')"

Args:
    query: SQL query to execute - can use simple table names or read_parquet()
    files: List of parquet file paths to query (typically from query_dataset results)
    include_schema: Whether to include schema information in the result
    
Returns:
    Query results and metadata

Inputs: query (required), files, include_schema.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    TDQS

    A4/5.0

    Scored across 10 tools

    Disambiguation4/5

    Most tools have distinct purposes, but there is some overlap between query_blockchain_sql and the combination of query_dataset + query_sql. The descriptions clarify that query_blockchain_sql is a convenience function combining the two, which helps reduce confusion, but agents might still need to decide between the separate or combined approach.

    Naming Consistency5/5

    All tool names follow a consistent verb_noun pattern with snake_case, such as get_latest_ethereum_block, list_available_sql_tables, and query_dataset. This consistency makes the tool set predictable and easy to navigate for agents.

    Tool Count5/5

    With 10 tools, the server is well-scoped for its purpose of blockchain data querying and SQL analysis. Each tool serves a clear role, from data retrieval (e.g., get_transaction_by_hash) to dataset exploration (e.g., lookup_dataset) and SQL execution (e.g., query_sql), without feeling bloated or sparse.

    Completeness5/5

    The tool set provides comprehensive coverage for blockchain data workflows, including data fetching (get_latest_ethereum_block, get_transaction_by_hash), dataset discovery (list_datasets, lookup_dataset), data download (query_dataset), SQL querying (query_sql, query_blockchain_sql), and schema inspection (get_sql_table_schema, list_available_sql_tables). There are no obvious gaps, and the tools support full CRUD-like operations for the domain.

    Maintenance

    ActivityInactive
    ResponsivenessNo recent community issues

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