query-onchain-data

A paid SQL query tool for reading decoded blockchain data on Base, including blocks, transactions, events, and transfers. SQL is a language for asking structured questions of a database.

In plain words
What is it for?
Use it to run SQL queries that examine Base events, transactions, blocks, and token transfers.
Why use it?
It lets you investigate Base blockchain activity with queries instead of manually inspecting individual blocks or transactions.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/nirholas/three.ws/query-onchain-data
Any agent
npx skills add nirholas/three.ws --skill query-onchain-data
Clone the repo
git clone --depth 1 https://github.com/nirholas/three.ws

Made for: Claude Code, Codex.

Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,386 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00042 $0.02386
Opus 5 $0.00021 $0.01193
Sonnet 5 $0.00008 $0.00477
Haiku 4.5 $0.00004 $0.00239

Measured 2d ago against content hash dd71ea2949a9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

query-onchain-data scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.agents/skills/query-onchain-data/SKILL.md · 214 lines

How it starts

The opening of the file, as written. The whole thing — 214 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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 [email protected] status

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

Executing a Query

npx [email protected] 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

Read the full file on GitHub · 214 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 214 lines · 42 tokens per session scan A dd71ea2949a9

Subscribe to this mod's changes

query-onchain-data is a skill published in the GitHub repository nirholas/three.ws (107 stars, last pushed 3d ago), licensed Apache-2.0. It adds 42 tokens to every session and 2,386 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

dual-replay

Run Sui dual execution replay between base and tip commits, recover failed steps, build, and commit replay instrumentation.

MystenLabs/sui · 27 tokens

sui-move-security-review

Use when auditing, reviewing, or hunting for vulnerabilities in Move code on Sui. Applies equally to source code (.move files) and to disassembly of compiled bytecode (on-chain packages). A checklist of invariants whose VIOLATION causes exploitable bugs: access control & capabilities, struct abilities & type safety…

MystenLabs/sui · 174 tokens

sui-and-move-tools

Use to get bytecode for a deployed Sui package and produce a disassembled working view. One GraphQL call fetches every module's raw bytecode bytes; sui move disassemble (already on the system, running sui prompt) produces .asm files for analysis. Trigger on "fetch this package's bytecode", "get me the .mv for package…

MystenLabs/sui · 105 tokens

analyzing-ethereum-smart-contract-vulnerabilities

Perform static and symbolic analysis of Solidity smart contracts using Slither and Mythril to detect reentrancy, integer overflow, access control, and other vulnerability classes before deployment to Ethereum mainnet.

xalgorix/xalgorix · 49 tokens

beacon-skill

Agent-to-agent protocol for social coordination, crypto payments, and P2P mesh.

Scottcjn/beacon-skill · 0 tokens

lineth-quickstart

Operating manual for the Lineth Stack quickstart — the Docker-Compose dev/demo stack at docs/getting-started/lineth-stack in the lineth-monorepo that boots a local Linea/Lineth L2 with Sepolia or local L1 finality. Use whenever you are working inside the lineth-stack quickstart and need to boot or run the stack…

LFDT-Lineth/lineth-monorepo · 228 tokens