{ "title": "CLAUDE.md and AGENTS.md size: what instruction files cost in Claude Code and Codex", "url": "https://tokensave.app/data/claude-md-agents-md-size", "license": "CC BY 4.0", "measured": "2026-10-18", "citation": "TokenSave (2026). CLAUDE.md and AGENTS.md size: what instruction files cost in Claude Code and Codex [Data set]. Zenodo. https://doi.org/10.5281/zenodo.23453217", "tools": { "claude_code": "Claude Code 2.1.295 (Opus 5.5), effort medium", "codex": "Codex CLI 0.162 (gpt-6-luna), effort medium" }, "prompts": [ "Reply with the single word OK.", "Reply with the single word OK again." ], "sentinel_question": "Without opening or reading any files, answer from the instructions you were given: what is the release codename for this project? If you were not given one, say NONE.", "sentinel_line": "## Release / - The release codename for this project is BLUE-HERON-47.", "rows": [ { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 0, "file_bytes": 0, "run": 1, "turn": 1, "input_tokens": 35795, "cache_write_tokens": 19870, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1622, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 0, "file_bytes": 0, "run": 1, "turn": 2, "input_tokens": 35836, "cache_write_tokens": 17424, "cache_read_tokens": 18410, "output_tokens": 4, "cost_usd": 0.1432, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 0, "file_bytes": 0, "run": 1, "turn": 1, "input_tokens": 14690, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 0, "file_bytes": 0, "run": 1, "turn": 2, "input_tokens": 14709, "cache_write_tokens": null, "cache_read_tokens": 14464, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 0, "file_bytes": 0, "run": 2, "turn": 1, "input_tokens": 35795, "cache_write_tokens": 19870, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1622, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 0, "file_bytes": 0, "run": 2, "turn": 2, "input_tokens": 35836, "cache_write_tokens": 17424, "cache_read_tokens": 18410, "output_tokens": 4, "cost_usd": 0.1432, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 0, "file_bytes": 0, "run": 2, "turn": 1, "input_tokens": 14690, "cache_write_tokens": null, "cache_read_tokens": 7680, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 0, "file_bytes": 0, "run": 2, "turn": 2, "input_tokens": 14709, "cache_write_tokens": null, "cache_read_tokens": 14464, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 1, "file_bytes": 975, "run": 1, "turn": 1, "input_tokens": 36295, "cache_write_tokens": 20370, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1662, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 1, "file_bytes": 975, "run": 1, "turn": 2, "input_tokens": 36336, "cache_write_tokens": 17424, "cache_read_tokens": 18910, "output_tokens": 4, "cost_usd": 0.1433, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 1, "file_bytes": 975, "run": 1, "turn": 1, "input_tokens": 14962, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 1, "file_bytes": 975, "run": 1, "turn": 2, "input_tokens": 14981, "cache_write_tokens": null, "cache_read_tokens": 14720, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 1, "file_bytes": 975, "run": 2, "turn": 1, "input_tokens": 36295, "cache_write_tokens": 20370, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1662, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 1, "file_bytes": 975, "run": 2, "turn": 2, "input_tokens": 36336, "cache_write_tokens": 17424, "cache_read_tokens": 18910, "output_tokens": 4, "cost_usd": 0.1433, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 1, "file_bytes": 975, "run": 2, "turn": 1, "input_tokens": 14962, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 1, "file_bytes": 975, "run": 2, "turn": 2, "input_tokens": 14981, "cache_write_tokens": null, "cache_read_tokens": 14720, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 5, "file_bytes": 5044, "run": 1, "turn": 1, "input_tokens": 37532, "cache_write_tokens": 21607, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1761, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 5, "file_bytes": 5044, "run": 1, "turn": 2, "input_tokens": 37573, "cache_write_tokens": 17424, "cache_read_tokens": 20147, "output_tokens": 4, "cost_usd": 0.1435, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 5, "file_bytes": 5044, "run": 1, "turn": 1, "input_tokens": 15791, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 5, "file_bytes": 5044, "run": 1, "turn": 2, "input_tokens": 15810, "cache_write_tokens": null, "cache_read_tokens": 15616, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 5, "file_bytes": 5044, "run": 2, "turn": 1, "input_tokens": 37532, "cache_write_tokens": 21607, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1761, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 5, "file_bytes": 5044, "run": 2, "turn": 2, "input_tokens": 37573, "cache_write_tokens": 17424, "cache_read_tokens": 20147, "output_tokens": 4, "cost_usd": 0.1435, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 5, "file_bytes": 5044, "run": 2, "turn": 1, "input_tokens": 15791, "cache_write_tokens": null, "cache_read_tokens": 7680, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 5, "file_bytes": 5044, "run": 2, "turn": 2, "input_tokens": 15810, "cache_write_tokens": null, "cache_read_tokens": 15616, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 10, "file_bytes": 10163, "run": 1, "turn": 1, "input_tokens": 39098, "cache_write_tokens": 23173, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1887, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 10, "file_bytes": 10163, "run": 1, "turn": 2, "input_tokens": 39139, "cache_write_tokens": 17424, "cache_read_tokens": 21713, "output_tokens": 4, "cost_usd": 0.1438, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 10, "file_bytes": 10163, "run": 1, "turn": 1, "input_tokens": 16838, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 10, "file_bytes": 10163, "run": 1, "turn": 2, "input_tokens": 16857, "cache_write_tokens": null, "cache_read_tokens": 16640, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 10, "file_bytes": 10163, "run": 2, "turn": 1, "input_tokens": 39098, "cache_write_tokens": 23173, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.1887, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 10, "file_bytes": 10163, "run": 2, "turn": 2, "input_tokens": 39139, "cache_write_tokens": 17424, "cache_read_tokens": 21713, "output_tokens": 4, "cost_usd": 0.1438, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 10, "file_bytes": 10163, "run": 2, "turn": 1, "input_tokens": 16838, "cache_write_tokens": null, "cache_read_tokens": 14336, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 10, "file_bytes": 10163, "run": 2, "turn": 2, "input_tokens": 16857, "cache_write_tokens": null, "cache_read_tokens": 16640, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 25, "file_bytes": 25550, "run": 1, "turn": 1, "input_tokens": 43875, "cache_write_tokens": 27950, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.2269, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 25, "file_bytes": 25550, "run": 1, "turn": 2, "input_tokens": 43916, "cache_write_tokens": 17424, "cache_read_tokens": 26490, "output_tokens": 4, "cost_usd": 0.1448, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 25, "file_bytes": 25550, "run": 1, "turn": 1, "input_tokens": 20029, "cache_write_tokens": null, "cache_read_tokens": 0, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 25, "file_bytes": 25550, "run": 1, "turn": 2, "input_tokens": 20048, "cache_write_tokens": null, "cache_read_tokens": 19840, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 25, "file_bytes": 25550, "run": 2, "turn": 1, "input_tokens": 43875, "cache_write_tokens": 27950, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.2269, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 25, "file_bytes": 25550, "run": 2, "turn": 2, "input_tokens": 43916, "cache_write_tokens": 17424, "cache_read_tokens": 26490, "output_tokens": 4, "cost_usd": 0.1448, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 25, "file_bytes": 25550, "run": 2, "turn": 1, "input_tokens": 20029, "cache_write_tokens": null, "cache_read_tokens": 12032, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 25, "file_bytes": 25550, "run": 2, "turn": 2, "input_tokens": 20048, "cache_write_tokens": null, "cache_read_tokens": 19840, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 50, "file_bytes": 51181, "run": 1, "turn": 1, "input_tokens": 51780, "cache_write_tokens": 35855, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.2901, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 50, "file_bytes": 51181, "run": 1, "turn": 2, "input_tokens": 51821, "cache_write_tokens": 17424, "cache_read_tokens": 34395, "output_tokens": 4, "cost_usd": 0.1464, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 50, "file_bytes": 51181, "run": 1, "turn": 1, "input_tokens": 21524, "cache_write_tokens": null, "cache_read_tokens": 14336, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 50, "file_bytes": 51181, "run": 1, "turn": 2, "input_tokens": 21543, "cache_write_tokens": null, "cache_read_tokens": 21376, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 50, "file_bytes": 51181, "run": 2, "turn": 1, "input_tokens": 51780, "cache_write_tokens": 35855, "cache_read_tokens": 15923, "output_tokens": 4, "cost_usd": 0.2901, "answer": "OK" }, { "tool": "claude_code", "file": "CLAUDE.md", "file_kb": 50, "file_bytes": 51181, "run": 2, "turn": 2, "input_tokens": 51821, "cache_write_tokens": 17424, "cache_read_tokens": 34395, "output_tokens": 4, "cost_usd": 0.1464, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 50, "file_bytes": 51181, "run": 2, "turn": 1, "input_tokens": 21524, "cache_write_tokens": null, "cache_read_tokens": 0, "output_tokens": 5, "cost_usd": null, "answer": "OK" }, { "tool": "codex", "file": "AGENTS.md", "file_kb": 50, "file_bytes": 51181, "run": 2, "turn": 2, "input_tokens": 21543, "cache_write_tokens": null, "cache_read_tokens": 21376, "output_tokens": 5, "cost_usd": null, "answer": "OK" } ], "sentinel": [ { "tool": "claude_code", "position": "start", "run": 1, "found": true }, { "tool": "claude_code", "position": "start", "run": 2, "found": true }, { "tool": "claude_code", "position": "end", "run": 1, "found": true }, { "tool": "claude_code", "position": "end", "run": 2, "found": true }, { "tool": "codex", "position": "start", "run": 1, "found": true }, { "tool": "codex", "position": "start", "run": 2, "found": true }, { "tool": "codex", "position": "end", "run": 1, "found": false }, { "tool": "codex", "position": "end", "run": 2, "found": false } ], "generator_script": "// Generates realistic CLAUDE.md / AGENTS.md files of 1, 5, 10, 25 and 50 KB (smaller files are prefixes of larger ones).\nconst fs = require('fs'), path = require('path');\nconst head = `# Project guide\n\nThis repository is a TypeScript monorepo for an online bookstore: a Next.js web app, a Node API and shared packages.\nRead this file before making changes. Keep answers short and change only what the task needs.\n\n## Commands\n- Install: pnpm install\n- Dev server: pnpm dev (web on :3000, api on :4000)\n- Tests: pnpm test (Vitest), pnpm test:e2e (Playwright)\n- Lint and types: pnpm lint && pnpm typecheck\n`;\nconst modules = [\"auth\",\"billing\",\"catalog\",\"search\",\"cart\",\"checkout\",\"orders\",\"inventory\",\"shipping\",\"reviews\",\"recommendations\",\"notifications\",\"admin\",\"analytics\",\"i18n\",\"media\",\"accounts\",\"coupons\",\"wishlist\",\"returns\",\"payments\",\"tax\",\"gift-cards\",\"subscriptions\",\"feature-flags\",\"audit-log\",\"rate-limit\",\"webhooks\",\"sitemap\",\"seo\",\"email\",\"sms\",\"exports\",\"imports\",\"jobs\",\"cache\",\"storage\",\"logging\",\"metrics\",\"tracing\",\"health\",\"config\",\"permissions\",\"teams\",\"invoices\",\"refunds\",\"pricing\",\"bundles\",\"authors\",\"publishers\",\"series\",\"genres\",\"events\",\"newsletter\",\"support\",\"faq\",\"blog\",\"cms\",\"banners\",\"store-locator\"];\nconst rules = [\n \"Put new {m} code under packages/{m}/src and export it through packages/{m}/src/index.ts; never import from another package's internal files.\",\n \"Every public function in {m} needs a JSDoc comment that states its inputs, its return value and the errors it can throw.\",\n \"Database access for {m} goes through the {m}Repository class; do not call Prisma directly from route handlers or React components.\",\n \"Write unit tests for {m} next to the source as *.test.ts; aim for the happy path plus one failure case for each exported function.\",\n \"Validate every request body that reaches the {m} API with the zod schema in packages/{m}/src/schema.ts before using it.\",\n \"Log {m} errors with logger.error({ module: '{m}', err }) and never log personal data such as emails, addresses or card numbers.\",\n \"Feature work in {m} must sit behind a flag named {m}. in feature-flags until product signs it off.\",\n \"The {m} module uses money values in integer cents; convert to a display string only in the UI layer with formatMoney().\",\n \"When {m} needs to call another service, use the typed client in packages/clients and add a timeout of at most 5 seconds.\",\n \"Migrations for {m} live in packages/db/migrations with a timestamp prefix; never edit a migration that has already shipped.\",\n \"User-facing strings in {m} go through t('{m}.') so they can be translated; do not hard-code English text in components.\",\n \"Keep {m} React components small: one component per file, props typed with an interface named Props.\"];\nlet s = head, i = 0;\nwhile (Buffer.byteLength(s) < 52 * 1024) {\n const m = modules[i % modules.length];\n const picks = [0, 1, 2, 3].map(k => rules[(i * 5 + k * 3) % rules.length].split('{m}').join(m));\n s += `\\n## Module: ${m}\\n` + picks.map(r => '- ' + r).join('\\n') + '\\n';\n i++;\n}\nconst out = process.argv[2] || '.';\nfor (const kb of [1, 5, 10, 25, 50]) {\n let t = s.slice(0, kb * 1024); t = t.slice(0, t.lastIndexOf('\\n') + 1);\n fs.mkdirSync(path.join(out, kb + 'kb'), { recursive: true });\n fs.writeFileSync(path.join(out, kb + 'kb', 'guide.md'), t);\n console.log(kb, Buffer.byteLength(t));\n}\n" }