Microsoft Clarity is an open-source TypeScript library that records website interactions and layout changes so they can be analyzed as behavioral data and replayed as sessions. Website developers use its instrumentation, decoding, visualization, and browser-devtools components to understand how users navigate and interact with sites while emphasizing privacy and performance. The catalogue entries provide agent instructions and an MCP integration for working with Clarity.
Borrowing it
Nothing to install: this file belongs to microsoft/clarity. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/microsoft/clarity/master/CLAUDE.mdgit clone --depth 1 https://github.com/microsoft/clarityWrote 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.
[](https://agentmods.dev/instructions/microsoft/clarity/claude-md)<a href="https://agentmods.dev/instructions/microsoft/clarity/claude-md"><img src="https://agentmods.dev/badge/instructions/microsoft/clarity/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>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.
<a href="https://agentmods.dev/instructions/microsoft/clarity/claude-md"><img src="https://agentmods.dev/badge/instructions/microsoft/clarity/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01626 | $0.01626 |
| Opus 5.5 | $0.00650 | $0.00650 |
| Sonnet 5.5 | $0.00325 | $0.00325 |
| Haiku 4.5 | $0.00163 | $0.00163 |
Grade A, and why
clarity 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.
This is a copy
94% identical to clarity copilot-instructions.md — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Clarity Development Guidelines
Repository Overview
Clarity is an open-source TypeScript behavioral analytics library for tracking user interactions and session replays. Monorepo with Lerna/Yarn workspaces:
- clarity-js (packages/clarity-js): Core instrumentation library
- clarity-decode (packages/clarity-decode): Data decoder
- clarity-visualize (packages/clarity-visualize): Session replay visualization
- clarity-devtools (packages/clarity-devtools): Chrome extension (private)
Stack: TypeScript, Rollup, TSLint, Playwright, Lerna, Yarn workspaces
clarity-js Performance & Bundle Size Priorities
Critical: clarity-js has two top priorities that must guide all development decisions:
-
Performance - As an analytics library running on diverse websites, clarity-js must not hurt website performance or impact metrics like INP (Interaction to Next Paint) or PLT (Page Load Time). Balance data collection needs with:
- Avoid blocking the main thread
- Minimize network requests
- Reduce payload size
-
Bundle Size - Small bundle size is crucial for loading clarity-js quickly and starting data collection as soon as possible. Every byte matters.
Build & Development Commands
Installation
ALWAYS run yarn install before building or testing. (~25s, peer dependency warnings are normal)
Building
yarn build # All packages (~45s, Lerna parallel build)
yarn build:js # clarity-js only (~20s)
yarn build:decode # clarity-decode only
yarn build:visualize # clarity-visualize only
yarn build:devtools # clarity-devtools only
Rollup + TypeScript → multiple formats (CJS, ESM, IIFE minified). Build artifacts auto-cleaned to build/ or extension/ (gitignored).
Build outputs per package:
- clarity-js:
clarity.js(CJS),clarity.module.js(ESM),clarity.min.js(minified), plus variants:clarity.extended.js,clarity.insight.js,clarity.performance.js,clarity.livechat.js, and dynamic module builds (clarity.tidio.js,clarity.crisp.js) - clarity-decode:
clarity.decode.js(CJS),clarity.decode.module.js(ESM),clarity.decode.min.js(minified) - clarity-visualize:
clarity.visualize.js(CJS),clarity.visualize.module.js(ESM),clarity.visualize.min.js(minified) - clarity-devtools: Output to
extension/directory for Chrome extension
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.
- 2mo ago First seen · 143 lines · 1,626 tokens per session scan A 436fa64d6262
clarity CLAUDE.md is an instructions file published in the GitHub repository microsoft/clarity (2,781 stars, last pushed yesterday), licensed MIT. It adds 1,626 tokens to every session, about $0.0065 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 94% identical to clarity copilot-instructions.md, differing in 4 lines, and is treated as a copy.
clarity CLAUDE.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| clarity CLAUDE.mdmicrosoft/clarity | Instructions file | 2.8k | yesterday | MIT | A | 1,626 | Claude Code |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | today | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | today | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | today | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |