metamask-connect-best-practices

metamask-connect-best-practices is a cursor rule for Cursor from MetaMask/metamask-connect-cursor-plugin. It costs 1,401 tokens per session, scanned A, original, MIT.

A set of coding rules for connecting applications to MetaMask, a cryptocurrency wallet, through its Connect SDK.

In plain words
What is it for?
Implementing or reviewing MetaMask connections for EVM blockchains, multiple blockchain types, or Solana in JavaScript applications.
Why use it?
It helps avoid incorrect imports, duplicate package versions, missing configuration, and connection-state or error-handling mistakes.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc).

Good fit Implementing or reviewing MetaMask connections for EVM blockchains, multiple blockchain types, or Solana in JavaScript applications.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices
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.

Clone the repo
git clone --depth 1 https://github.com/MetaMask/metamask-connect-cursor-plugin

Made for: Cursor.

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.

agentmods badge for metamask-connect-best-practices

README.md
[![agentmods](https://agentmods.dev/badge/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices/github.svg)](https://agentmods.dev/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices)
Your own site
<a href="https://agentmods.dev/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices"><img src="https://agentmods.dev/badge/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices/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.

agentmods 80×15 button for metamask-connect-best-practices

Your own site · 80×15
<a href="https://agentmods.dev/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices"><img src="https://agentmods.dev/badge/rules/metamask/metamask-connect-cursor-plugin/metamask-connect-best-practices.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 1,401 This file is loaded in full into every session.
When invoked 1,401 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 $0.01401 $0.01401
Opus 5 $0.00700 $0.00700
Sonnet 5 $0.00280 $0.00280
Haiku 4.5 $0.00140 $0.00140

Measured 9d ago against content hash 8376d3159607, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

metamask-connect-best-practices 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 9d 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.

rules/metamask-connect-best-practices.mdc · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MetaMask Connect Best Practices

Import Paths

  • Import EVM client from @metamask/connect-evm
  • Import multichain client from @metamask/connect-multichain
  • Import Solana client from @metamask/connect-solana
  • Never import from internal sub-packages like @metamask/connect/dist/... or @metamask/connect-evm/src/...
  • Use the wagmi connector from the published entrypoint your installed version exposes; do not assume @metamask/connect-evm/wagmi exists unless your package version exports it
  • @metamask/connect-multichain is a regular dependency of both @metamask/connect-evm and @metamask/connect-solana (since 2.1.0) and is installed transitively — you do not need to add it yourself. (Only the 2.0.0 releases briefly made it a peer dependency.) Both clients warn at runtime on duplicate or mismatched @metamask/connect-multichain resolutions; if you do depend on it directly (e.g. to use createMultichainClient), use ^1.0.0 — it is a stable 1.x package following strict semver

Required Configuration

  • dapp.name is always required — it appears in the MetaMask connection prompt
  • dapp.url is required in Node.js and React Native environments (no window.location available)
  • dapp.url in browser can default to window.location.href but explicit is safer
  • dapp.iconUrl is optional — displayed in MetaMask connection UI
  • dapp.base64Icon is an alternative to iconUrl — pass a base64-encoded icon string directly (useful when a hosted URL is unavailable, e.g., in React Native)

Supported Networks

  • Every chain the dApp interacts with must be in api.supportedNetworks with a reachable RPC URL
  • Use getInfuraRpcUrls({ infuraApiKey: 'API_KEY', chainIds?: Hex[] }) to populate common EVM chains — it returns a hex-keyed map for createEVMClient
  • Use getInfuraRpcUrls({ infuraApiKey: 'API_KEY', caipChainIds?: string[] }) to populate CAIP-2 chains for createMultichainClient
  • Use getInfuraRpcUrls({ infuraApiKey: 'API_KEY', networks: SolanaNetwork[] }) from @metamask/connect-solana to populate a network-name-keyed map for createSolanaClientnetworks is required
  • Chain 0x1 (Ethereum mainnet) is auto-included in the EVM connect() permission request if not specified — but it is not auto-added to supportedNetworks, which must list every chain explicitly
  • Making an RPC request whose active chain is missing from supportedNetworks throws "not configured in supportedNetworks" (the check runs in the provider's request() path, not in connect())

Read the full file on GitHub · 75 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. 9d ago First seen · 75 lines · 1,401 tokens per session scan A 8376d3159607

Subscribe to this mod's changes

metamask-connect-best-practices is a cursor rule published in the GitHub repository MetaMask/metamask-connect-cursor-plugin (2 stars, last pushed 2mo ago), licensed MIT. It adds 1,401 tokens to every session, about $0.0070 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 2026-08-31.

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