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a2db: Instructions file for Claude Code

CLAUDE.md

a2db CLAUDE.md is an instructions file for Claude Code from yoselabs/a2db. It costs 469 tokens per session, scanned A, original, Apache-2.0.

Repository instructions for a2db, a tool that lets AI agents query databases through a command line or an MCP server.

In plain words
What is it for?
Use them when changing a2db, especially when running checks, editing database connections or SQL handling, or deciding which actions require permission.
Why use it?
They give coding agents the project’s architecture, commands, safety rules, and testing expectations so they can work without guessing.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md.

This is yoselabs/a2db's own configuration. It tells Claude Code how to work on a2db itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything a2db configures →

not rated 2repo 6mo ago A scan 469 tokens original Apache-2.0
View source ↗ yoselabs/a2db
Reuse

Borrowing it

Nothing to install: this file belongs to yoselabs/a2db. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/yoselabs/a2db/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/yoselabs/a2db

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
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Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
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Per session 469 This file is loaded in full into every session.
When invoked 469 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00469 $0.00469
Opus 5.5 $0.00188 $0.00188
Sonnet 5.5 $0.00094 $0.00094
Haiku 4.5 $0.00047 $0.00047

Measured 2mo ago against content hash 21ed262b4492, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

a2db CLAUDE.md 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 2mo 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.

CLAUDE.md · 40 lines

What it actually says

a2db — Agent-to-Database

CLI and MCP server for AI agents to query databases. Two frontends (CLI + MCP), one core.

Architecture

  • src/a2db/connections.py — ConnectionStore: save/load/list connection TOML files
  • src/a2db/drivers.py — DriverRegistry: DSN scheme → DBAPI 2.0 driver resolution
  • src/a2db/sql.py — SQLGlot wrapping: pagination, read-only validation
  • src/a2db/executor.py — QueryExecutor: named batch queries with pagination
  • src/a2db/schema.py — SchemaExplorer: progressive schema discovery
  • src/a2db/formatter.py — Output formatting: TSV and JSON renderers
  • src/a2db/cli.py — Click CLI frontend (thin wrapper)
  • src/a2db/mcp_server.py — MCP server frontend (thin wrapper)

Dev Commands

  • Full gate: make check (lint + test + security)
  • Run tests: make test (includes coverage, fails under 90%)
  • Lint: make lint or agent-harness lint (check only, never modifies files — safe to run anytime)
  • Fix: make fix or agent-harness fix (auto-fix, then runs lint to verify)
  • Coverage diff: make coverage-diff (changed lines must be 95%+ covered)
  • Security: agent-harness security-audit (deps + secrets)
  • Config check: agent-harness init (checks project hygiene)
  • Build: make build
  • Bootstrap: make bootstrap (installs deps, requires agent-harness CLI)

Pre-commit hooks run fix then lint automatically on every commit. Never truncate lint or test output — read the full error.

Never

  • Never commit .env files or database credentials
  • Never execute destructive SQL (DROP, TRUNCATE, DELETE without WHERE) without explicit user confirmation

Ask First

  • Before changing CLI argument names or command structure (breaking change for users)
  • Before adding new dependencies
  • Before changing MCP tool signatures (breaking change for MCP clients)
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. 2mo ago First seen · 40 lines · 469 tokens per session scan A 21ed262b4492

Subscribe to this mod's changes

a2db CLAUDE.md is an instructions file published in the GitHub repository yoselabs/a2db (2 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 469 tokens to every session, about $0.0019 per session on Opus 5.5. 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 2026-08-31.

Backend and APIsDatabasesai-agentsclimcpmcp-servermodel-context-protocol
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