Crypto Regime MCP

A stdio MCP bridge for signal-api. It connects Claude Desktop, Claude Code, Cursor or any stdio MCP client to the remote Streamable HTTP MCP endpoint and pays for tools in one of two ways:

• x402: signs USDC payments on Base with a local EVM wallet.

• Prepaid credits: sends an X-API-Key to the REST /v1/* routes.

Not Signal Messenger. signal-api is a crypto market-signal service. This package has no relationship with Signal Messenger or its messaging app.

What it does

• Speaks MCP over stdio to your client.

• Connects to https://signal-api.shicoars.workers.dev/mcp using Streamable HTTP.

• Exposes the remote tools locally, including their input schemas.

• With SIGNAL_API_KEY, serves paid tools through /v1/* using prepaid credits and adds get_credit_balance.

• Without SIGNAL_API_KEY, detects x402 PaymentRequired responses and signs USDC payments on Base automatically.

• Enforces a per-session spending limit with MAX_SPEND_USDC in x402 mode.

The bridge is useful for clients that only support stdio MCP and do not have native x402 payment support. Clients with native x402 support can connect directly to the remote URL.

Related MCP server: x402-mcp-demo

Payment methods

1. Prepaid credits (SIGNAL_API_KEY)

Set SIGNAL_API_KEY to a credit key (sk_...) bought from signal-api. The bridge then:

• Calls /v1/signal, /v1/market-scan, /v1/trend/{asset}, /v1/regime/{asset} and /v1/indicators/{asset} with the X-API-Key header.

• Does not sign x402 payments and does not need EVM_PRIVATE_KEY.

• Uses the free /free/{asset} route for get_sample.

• Exposes get_credit_balance, which reads GET /credits/balance.

• Reports the credits charged and remaining balance in _meta under signal-api/credits when the API returns those headers.

SIGNAL_API_KEY takes precedence when both variables are set.

2. x402 (EVM_PRIVATE_KEY)

Without SIGNAL_API_KEY, the bridge works as before: it connects to the remote MCP endpoint, receives x402 PaymentRequired results, signs USDC payments on Base with EVM_PRIVATE_KEY, and retries the call. MAX_SPEND_USDC caps the amount the bridge may authorize per session.

Tools and prices

Network for x402: Base mainnet (eip155:8453), paid in USDC.

Credits are charged per request: get_market_scan costs 10 credits and the other paid tools cost 1 credit. Insufficient credits return HTTP 402 with the current balance; an invalid key returns HTTP 401.

Requirements

• Node.js 20 or newer

• Either a credit key from signal-api, or an EVM wallet private key with a small USDC balance on Base

• An MCP client that supports stdio servers (Claude Desktop, Claude Code, Cursor, or another MCP-compatible client)

Installation

Run the published package with npx:

npx -y @shicodiez/crypto-regime-mcp

Or install it globally:

npm install -g @shicodiez/crypto-regime-mcp

From source:

git clone https://github.com/Shicodiez/crypto-regime-mcp.git
cd crypto-regime-mcp
npm install

Run the bridge in credit mode:

SIGNAL_API_KEY=sk_... node src/index.js

Or in x402 mode:

EVM_PRIVATE_KEY=0x... MAX_SPEND_USDC=1 node src/index.js

On Windows PowerShell:

$env:SIGNAL_API_KEY = "sk_..."
node src/index.js

$env:EVM_PRIVATE_KEY = "0x..."
$env:MAX_SPEND_USDC = "1"
node src/index.js

The process communicates over stdio. Diagnostics are written to stderr.

Buying a credit pack

Buy a pack with x402. The starter pack costs 5 USDC and returns 2,000 credits; the pro pack costs 20 USDC and returns 10,000 credits.

POST https://signal-api.shicoars.workers.dev/credits/buy/starter

The first request without payment returns HTTP 402 with the x402 requirements in the PAYMENT-REQUIRED header. Sign the USDC payment on Base with any x402-capable client and retry the same request with the signed payload:

curl -i -X POST https://signal-api.shicoars.workers.dev/credits/buy/starter \
  -H "PAYMENT-SIGNATURE: <signed x402 payment payload>"

A successful response looks like:

{
  "key": "sk_...",
  "key_type": "api_key",
  "pack": "starter",
  "credits": 2000,
  "balance": 2000,
  "payer": "0x...",
  "transaction": "0x...",
  "note": "Store this key now. It is not stored and cannot be recovered."
}

Store the key immediately: signal-api stores only its SHA-256 hash and cannot show it again. Then set SIGNAL_API_KEY=sk_... in your MCP client and check the balance at any time:

curl https://signal-api.shicoars.workers.dev/credits/balance \
  -H "X-API-Key: sk_..."

The same header also works directly on /signal, /p/{id} and /v1/*.

Configuration

Claude Desktop

Edit the Claude Desktop configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

Credit mode:

{
  "mcpServers": {
    "crypto-regime": {
      "command": "npx",
      "args": ["-y", "@shicodiez/crypto-regime-mcp"],
      "env": {
        "SIGNAL_API_KEY": "sk_..."
      }
    }
  }
}

x402 mode: replace SIGNAL_API_KEY with EVM_PRIVATE_KEY and optionally MAX_SPEND_USDC.

Restart Claude Desktop after saving the file.

Claude Code

Credit mode:

claude mcp add crypto-regime \
  --env SIGNAL_API_KEY=sk_... \
  -- npx -y @shicodiez/crypto-regime-mcp

x402 mode:

claude mcp add crypto-regime \
  --env EVM_PRIVATE_KEY=0x... \
  --env MAX_SPEND_USDC=1 \
  -- npx -y @shicodiez/crypto-regime-mcp

If your Claude Code version supports remote MCP with x402 payments, you can add the hosted endpoint directly instead:

claude mcp add --transport http crypto-regime \
  https://signal-api.shicoars.workers.dev/mcp

For credit mode or automatic x402 payments, use the stdio bridge above.

Cursor

Add the server to ~/.cursor/mcp.json (global) or .cursor/mcp.json in your project. Credit mode:

{
  "mcpServers": {
    "crypto-regime": {
      "command": "npx",
      "args": ["-y", "@shicodiez/crypto-regime-mcp"],
      "env": {
        "SIGNAL_API_KEY": "sk_..."
      }
    }
  }
}

x402 mode: replace SIGNAL_API_KEY with EVM_PRIVATE_KEY and optionally MAX_SPEND_USDC.

Reload Cursor after saving the file.

Remote URL

The hosted MCP server is:

https://signal-api.shicoars.workers.dev/mcp

Transport: Streamable HTTP.

• Free tools work without authentication or payment.

• Paid MCP tools return an x402 PaymentRequired result.

• An x402-capable client can pay directly.

• Clients without native x402 support can use this stdio bridge in x402 mode.

• Credit keys can also call the REST routes directly with X-API-Key.

Security

• Use a dedicated wallet in x402 mode. Do not use a wallet that holds savings or other assets. Fund it with only the amount you are willing to spend.

• Set MAX_SPEND_USDC in x402 mode. The default is 1 USDC per session. The bridge refuses payments that would exceed the limit.

• Protect SIGNAL_API_KEY. Treat it like cash: anyone with the key can spend its credits. Do not commit it to a repository.

• The private key and credit key are stored in plain text in your MCP client configuration. Protect that file and never commit it.

• Never commit .env files or keys. The included .gitignore excludes common local secret files.

• Review payments. In x402 mode the bridge logs authorized amounts and recipients to stderr. Check the wallet balance and transaction history regularly.

• The bridge only sends EVM_PRIVATE_KEY to the local signing library; it is never sent to signal-api. SIGNAL_API_KEY is sent only to signal-api.

Development

Run the tests:

npm test

Build (syntax-check the published sources):

npm run build

The test suite covers the session spending tracker, USDC amount conversion, credit-mode route mapping, credit error handling and configuration precedence.

License

MIT. See LICENSE.