query-onchain-data

name	query-onchain-data
description	Query onchain data on Base using the CDP SQL API via x402. Use when you or your user want to view onchain information about decoded blocks, transactions, and events.
user-invocable	true
disable-model-invocation	false
allowed-tools	["Bash(npx awal@2.10.0 status*)","Bash(npx awal@2.10.0 balance*)","Bash(npx awal@2.10.0 x402 pay *)"]
metadata	{"category":"wallet/payments","cross-platform-safe":false,"pack":"three-ws-skills"}

Query Onchain Data on Base

Use the CDP SQL API to query onchain data (events, transactions, blocks, transfers) on Base. Queries are executed via x402 and are charged per query.

Confirm wallet is initialized and authed

npx awal@2.10.0 status

If the wallet is not authenticated, refer to the authenticate-wallet skill.

Executing a Query

npx awal@2.10.0 x402 pay https://x402.cdp.coinbase.com/platform/v2/data/query/run -X POST -d '{"sql": "<YOUR_QUERY>"}' --json

IMPORTANT: Always single-quote the -d JSON string to prevent bash variable expansion.

Input Validation

Before constructing the command, validate inputs to prevent shell injection:

• SQL query: Always embed the query inside a single-quoted JSON string (-d '{"sql": "..."}'). Never use double quotes for the outer -d wrapper, as this enables shell expansion of $ and backticks within the query.
• Addresses: Must be valid 0x hex addresses (^0x[0-9a-fA-F]{40}$). Reject any value containing shell metacharacters.

Do not pass unvalidated user input into the command.

CRITICAL: Indexed Fields

Queries against base.events MUST filter on indexed fields to avoid full table scans. The indexed fields are:

Indexed Field	Use For
event_signature	Filter by event type. Use this instead of event_name for performance.
address	Filter by contract address.
block_timestamp	Filter by time range.

Always include at least one indexed field in your WHERE clause. Combining all three gives the best performance.

CoinbaseQL Syntax

CoinbaseQL is a SQL dialect based on ClickHouse. Supported features:

• Clauses: SELECT (DISTINCT), FROM, WHERE, GROUP BY, ORDER BY (ASC/DESC), LIMIT, WITH (CTEs), UNION (ALL/DISTINCT)
• Joins: INNER, LEFT, RIGHT, FULL with ON
• Operators: =, !=, <>, <, >, <=, >=, +, -, *, /, %, AND, OR, NOT, BETWEEN, IN, IS NULL, LIKE
• Expressions: CASE/WHEN/THEN/ELSE, CAST (both CAST() and :: syntax), subqueries, array/map indexing with [], dot notation
• Literals: Array [...], Map {...}, Tuple (...)
• Functions: Standard SQL functions, lambda functions with -> syntax

Available Tables

base.events

Decoded event logs from smart contract interactions. This is the primary table for most queries.

Column	Type	Description
log_id	String	Unique log identifier
block_number	UInt64	Block number
block_hash	FixedString(66)	Block hash
block_timestamp	DateTime64(3, 'UTC')	Block timestamp (INDEXED)
transaction_hash	FixedString(66)	Transaction hash
transaction_to	FixedString(42)	Transaction recipient
transaction_from	FixedString(42)	Transaction sender
log_index	UInt32	Log index within block
address	FixedString(42)	Contract address (INDEXED)
topics	Array(FixedString(66))	Event topics
event_name	LowCardinality(String)	Decoded event name
event_signature	LowCardinality(String)	Event signature (INDEXED - prefer over event_name)
parameters	Map(String, Variant(Bool, Int256, String, UInt256))	Decoded event parameters
parameter_types	Map(String, String)	ABI types for parameters
action	Enum8('removed' = -1, 'added' = 1)	Added or removed (reorg)

base.transactions

Complete transaction data.

Column	Type	Description
block_number	UInt64	Block number
block_hash	String	Block hash
transaction_hash	String	Transaction hash
transaction_index	UInt64	Index in block
from_address	String	Sender address
to_address	String	Recipient address
value	String	Value transferred (wei)
gas	UInt64	Gas limit
gas_price	UInt64	Gas price
input	String	Input data
nonce	UInt64	Sender nonce
type	UInt64	Transaction type
max_fee_per_gas	UInt64	EIP-1559 max fee
max_priority_fee_per_gas	UInt64	EIP-1559 priority fee
chain_id	UInt64	Chain ID
v	String	Signature v
r	String	Signature r
s	String	Signature s
is_system_tx	Bool	System transaction flag
max_fee_per_blob_gas	String	Blob gas fee
blob_versioned_hashes	Array(String)	Blob hashes
timestamp	DateTime	Block timestamp
action	Int8	Added (1) or removed (-1)

base.blocks

Block-level metadata.

Column	Type	Description
block_number	UInt64	Block number
block_hash	String	Block hash
parent_hash	String	Parent block hash
timestamp	DateTime	Block timestamp
miner	String	Block producer
nonce	UInt64	Block nonce
sha3_uncles	String	Uncles hash
transactions_root	String	Transactions merkle root
state_root	String	State merkle root
receipts_root	String	Receipts merkle root
logs_bloom	String	Bloom filter
gas_limit	UInt64	Block gas limit
gas_used	UInt64	Gas used in block
base_fee_per_gas	UInt64	Base fee per gas
total_difficulty	String	Total chain difficulty
size	UInt64	Block size in bytes
extra_data	String	Extra data field
mix_hash	String	Mix hash
withdrawals_root	String	Withdrawals root
parent_beacon_block_root	String	Beacon chain parent root
blob_gas_used	UInt64	Blob gas used
excess_blob_gas	UInt64	Excess blob gas
transaction_count	UInt64	Number of transactions
action	Int8	Added (1) or removed (-1)

Example Queries

Get recent USDC Transfer events with decoded parameters

SELECT
  parameters['from'] AS sender,
  parameters['to'] AS to,
  parameters['value'] AS amount,
  address AS token_address
FROM base.events
WHERE
  event_signature = 'Transfer(address,address,uint256)'
  AND address = '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913'
  AND block_timestamp >= now() - INTERVAL 7 DAY
LIMIT 10

Get transactions from a specific address

npx awal@2.10.0 x402 pay https://x402.cdp.coinbase.com/platform/v2/data/query/run -X POST -d '{"sql": "SELECT transaction_hash, to_address, value, gas, timestamp FROM base.transactions WHERE from_address = lower('\''0xYOUR_ADDRESS'\'') AND timestamp >= now() - INTERVAL 1 DAY LIMIT 10"}' --json

Count events by type for a contract in the last hour

npx awal@2.10.0 x402 pay https://x402.cdp.coinbase.com/platform/v2/data/query/run -X POST -d '{"sql": "SELECT event_signature, count(*) as cnt FROM base.events WHERE address = lower('\''0xCONTRACT_ADDRESS'\'') AND block_timestamp >= now() - INTERVAL 1 HOUR GROUP BY event_signature ORDER BY cnt DESC LIMIT 20"}' --json

Get latest block info

npx awal@2.10.0 x402 pay https://x402.cdp.coinbase.com/platform/v2/data/query/run -X POST -d '{"sql": "SELECT block_number, timestamp, transaction_count, gas_used FROM base.blocks ORDER BY block_number DESC LIMIT 1"}' --json

Common Contract Addresses (Base)

Token	Address
USDC	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
WETH	0x4200000000000000000000000000000000000006

Best Practices

1. Always filter on indexed fields (event_signature, address, block_timestamp) in base.events queries.
2. Never use SELECT * - specify only the columns you need.
3. Always include a LIMIT clause to bound result size.
4. Use event_signature instead of event_name for filtering - it is indexed and much faster.
5. Use time-bounded queries with block_timestamp to narrow the scan range.
6. Always wrap address values in lower() - the database stores lowercase addresses but users may provide checksummed (mixed-case) addresses. Use address = lower('0xAbC...') not address = '0xAbC...'.
7. Common event signatures: Transfer(address,address,uint256), Approval(address,address,uint256), Swap(address,uint256,uint256,uint256,uint256,address).

Prerequisites

• Must be authenticated (npx awal@2.10.0 status to check, see authenticate-wallet skill)
• Wallet must have sufficient USDC balance (npx awal@2.10.0 balance to check)
• Each query costs $0.10 (100000 USDC atomic units)

Error Handling

• "Not authenticated" - Run awal auth login <email> first, or see authenticate-wallet skill
• "Insufficient balance" - Fund wallet with USDC; see fund skill
• Query timeout or error - Ensure you are filtering on indexed fields and using a LIMIT