MCP Wallet Signer

[!WARNING] Superseded by browser-web3-signer — the same browser-wallet signing flow, reimplemented in Rust with a CLI plus Rust/TypeScript/Go libraries. mcp-wallet-signer still works, but new development happens there.

Your private keys never leave your browser. Every transaction requires explicit user approval in your wallet.

Most blockchain MCPs require you to paste a private key into a config file — giving the AI agent full, unsupervised access to your funds. MCP Wallet Signer takes a different approach: it routes every transaction to your actual browser wallet — EVM wallets (MetaMask, Rabby, …) via EIP-6963, and TRON via TronLink — so you review and approve each action just like any other dapp interaction. No keys in config files, no risk of silent transactions.

Compatible With

Works with any MCP-compatible client via stdio transport.

Installation

Claude Code CLI

claude mcp add wallet-signer -- npx -y mcp-wallet-signer

(The name wallet-signer is just the MCP server identifier — pick anything you like. Legacy evm-wallet still works for users who installed before TRON support landed.)

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "wallet-signer": {
      "command": "npx",
      "args": ["-y", "mcp-wallet-signer"]
    }
  }
}

Run directly

npx -y mcp-wallet-signer
pnpx mcp-wallet-signer
bunx mcp-wallet-signer

MCP Tools

EVM (MetaMask / Rabby / any EIP-6963 wallet)

Tool	Description	Browser Required
connect_wallet	Connect wallet, return address	Yes
send_transaction	Send ETH/tokens, call contracts	Yes
sign_message	Sign arbitrary message (personal_sign)	Yes
sign_typed_data	Sign EIP-712 typed data	Yes
get_balance	Read ETH balance (via RPC)	No
get_token_balance	Read ERC-20 balance (balanceOf/decimals/symbol)	No

TRON (TronLink)

Tool	Description	Browser Required
tron_connect_wallet	Connect TronLink, return Base58 (T…) address	Yes
tron_send_transaction	Native TRX transfer	Yes
tron_trigger_contract	TRC-20 / smart-contract call via triggerSmartContract	Yes
tron_sign_message	Sign arbitrary message (signMessageV2)	Yes
tron_sign_typed_data	Sign TIP-712 typed data	Yes
tron_get_balance	Read TRX balance (via TronGrid)	No
tron_get_token_balance	Read TRC-20 balance (balanceOf/decimals/symbol)	No

How It Works

1. Agent calls an MCP tool (e.g., send_transaction or tron_send_transaction)
2. Server opens browser to a local signing page (EVM and TRON each run their own HTTP bridge on a separate port)
3. User connects wallet and approves the action — in MetaMask/Rabby/etc. for EVM, in TronLink for TRON
4. Result (address, tx hash, signature) returned to agent

Screenshots below show the EVM approval UI; the TRON UI mirrors the same card layout with TronLink-specific copy and TRX denomination.

Connect Wallet	Send Transaction	Sign Message

Supported Chains

Built-in RPC URLs for:

• Ethereum (1)
• Sepolia (11155111)
• Polygon (137)
• Arbitrum One (42161)
• Optimism (10)
• Base (8453)
• Avalanche (43114)
• BNB Smart Chain (56)

Supported TRON Networks

• Tron Mainnet
• Shasta Testnet
• Nile Testnet

Configuration

Environment variables (optional):

Variable	Description	Default
EVM_MCP_PORT	EVM HTTP server port	3847
EVM_MCP_DEFAULT_CHAIN	Default EVM chain ID	1
TRON_MCP_PORT	TRON HTTP server port	3848
TRON_MCP_DEFAULT_NETWORK	Default TRON network (mainnet/shasta/nile)	mainnet

Packages

This is a monorepo with three published packages plus one internal one:

Package	Published	Description
wallet-signer-core	internal	Chain-agnostic primitives (PendingStore, HTTP bridge, errors). Bundled into each chain package at build time — never installed directly.
browser-evm-signer	npm + JSR	Standalone library — sign EVM transactions via MetaMask/Rabby/any EIP-6963 wallet
browser-tron-signer	npm + JSR	Standalone library — sign TRON transactions via TronLink
mcp-wallet-signer	npm	MCP server — exposes the EVM and TRON signers as MCP tools for AI agents

Use the chain-specific packages directly if you want browser-based signing in your own Node.js/Deno app without MCP.

Development

Requires Deno v2.0+.

# Install all dependencies
deno task install:all

# Type check + lint + format check (all packages)
deno task check:all

# Run tests
deno task test:all

# Build all npm packages
deno task build:all

# Format code
deno task fmt

Manual signing CLI

A signer-cli script triggers the same flows that the MCP tools do, but from your shell — useful for smoke-testing against a real wallet without going through an MCP client.

# Discover subcommands
deno task cli                                 # top-level help
deno task cli evm help                        # EVM subcommands
deno task cli tron help                       # TRON subcommands
deno task cli evm send-transaction --help     # subcommand flags

# Examples (each opens a browser; sign in MetaMask / TronLink)
deno task cli evm  connect --chain 1
deno task cli evm  send-transaction --to 0x... --value 1000000000000000000
deno task cli evm  sign-message --message "hello"
deno task cli tron connect --network mainnet
deno task cli tron send-trx --to T... --amount 1000000
deno task cli tron trigger-contract --contract T... \
    --selector 'transfer(address,uint256)' \
    --params '[{"type":"address","value":"T..."},{"type":"uint256","value":"1000000"}]'
deno task cli tron get-balance --address T...   # no browser

The approval URL is always printed up-front, and every browser-interacting subcommand (both chains, every flow except get-balance which doesn't open a browser) accepts --browser <name> and --print:

# Pick a specific browser (the one that has TronLink / MetaMask installed)
deno task cli evm  connect --browser firefox
deno task cli evm  sign-message --message "hi" --browser chrome
deno task cli tron send-trx --to T... --amount 1000000 --browser edge
deno task cli tron trigger-contract --contract T... --selector 'transfer(address,uint256)' \
    --params '[...]' --browser /usr/bin/brave-browser

# Print the URL only — don't auto-open anything. Open it manually wherever you like
deno task cli evm  send-transaction --to 0x... --value 1000 --print
deno task cli evm  sign-typed-data --json typed.json --print
deno task cli tron connect --network shasta --print
deno task cli tron sign-message --message "hello" --print

--browser <name> accepts chrome, firefox, edge, safari, or a binary path. Useful when your system default doesn't have the wallet extension installed.

Per-package deno task trigger ... works too if you're already inside packages/browser-evm-signer/ or packages/browser-tron-signer/.

Project Structure

tools/
└── signer-cli.ts            # Root dispatcher → per-package trigger CLIs

packages/
├── wallet-signer-core/      # Chain-agnostic primitives (npm: wallet-signer-core)
│   ├── src/                  # PendingStore, HTTP bridge, errors, browser opener
│   ├── tests/                # Core unit tests
│   └── scripts/build-npm.ts
│
├── browser-evm-signer/      # EVM signing library (npm: browser-evm-signer)
│   ├── src/                  # EVM types, viem transport, EIP-6963 approval UI
│   ├── tools/trigger.ts      # Manual-trigger CLI
│   ├── tests/                # Unit, e2e (HTTP), and e2e-browser (Playwright) tests
│   └── scripts/build-npm.ts
│
├── browser-tron-signer/     # TRON signing library (npm: browser-tron-signer)
│   ├── src/                  # TRON types, TronLink approval UI, TronGrid balance fetch
│   ├── tools/trigger.ts      # Manual-trigger CLI
│   ├── tests/                # Unit, e2e (HTTP), and e2e-browser (Playwright) tests
│   └── scripts/build-npm.ts
│
└── mcp-wallet-signer/       # MCP server layer (npm: mcp-wallet-signer)
    ├── src/                  # MCP tool definitions + CLI entry
    └── scripts/build-npm.ts

A Deno workspace declaration at the root makes each member's import map visible to root-level scripts (notably tools/signer-cli.ts resolving wallet-signer-core).

All packages are built with dnt and use node: builtins (no Deno-specific APIs) so the npm bundles run under Node.js.

License

MIT