# x402-mcp [Health: Active] **Category:** 💰 Finance & Fintech **Repository:** https://github.com/CarbonCashmere/x402-mcp **GitHub Stars:** 0 **Views:** 0 **Installs:** 0 **Upvotes:** 0 **Directory Page:** https://allmcps.com/mcp/x402-mcp ## Description 177 crypto market intel endpoints with auto x402 USDC micropayments from your AI agent ## Claude Desktop Quick Installation Install path detected from listing signals. Uses `npx` (confidence: high): ```json "mcpServers": { "x402-mcp": { "command": "npx", "args": ["-y","@carbon-cashmere/x402-mcp"] } } ``` ## Documentation & README # @carbon-cashmere/x402-mcp MCP server that exposes [Carbon & Cashmere's](https://api.carbon-cashmere.de) 177 crypto market intelligence endpoints to your AI agent — with **automatic x402 USDC micropayments** from your wallet. ## What you get When this MCP is installed, your AI agent can call tools like: - `get_v1_news` — analyzed crypto news with sentiment + market impact - `get_v1_stablecoins` — total market cap, per-coin supply, chain distribution - `get_v1_onchain_btc` — Bitcoin on-chain metrics (hash-rate, mempool, miner flows) - `get_v1_bittensor_leaderboard` — top-100 Bittensor miners by emission - `get_v1_mantis_realized_accuracy` — MANTIS subnet (UID 253) realized accuracy track-record - `get_v1_intel_snapshot` — aggregated market intel snapshot - … plus subscriptions ($10/day, $50/week, $200/month), sponsor tiers ($500–$50000), and 170+ research endpoints priced **$0.003 – $0.50 per call** **177 paid endpoints total.** Default exposes top 100 (curated by revenue + popularity). Set `X402_TOOL_LIMIT=177` to expose all incl. per-coin variants. Each tool invocation triggers a single USDC micropayment from your configured wallet. No subscription. No API key. Pay only for what you use. ## Install ### Claude Desktop Add to `~/Library/Application Support/Claude/claude_desktop_config.json` (macOS) or `%APPDATA%\Claude\claude_desktop_config.json` (Windows): ```json { "mcpServers": { "carbon-cashmere": { "command": "npx", "args": ["-y", "@carbon-cashmere/x402-mcp"], "env": { "EVM_PRIVATE_KEY": "0x_your_evm_private_key_here", "SVM_PRIVATE_KEY": "your_base58_solana_private_key_here_optional" } } } } ``` Restart Claude Desktop. The top 100 Carbon & Cashmere tools (curated by revenue + popularity) appear in your tool palette. ### Cursor / Cline / Continue Same JSON config, paste into your MCP settings panel. ## Wallet setup > **Security: use a dedicated spending wallet, not your main wallet.** > Your `EVM_PRIVATE_KEY` sits in plaintext in your Claude Desktop config. Any > process on the host with read access to that file gets the key. Treat it as > a hot wallet you would not mind losing: fund it with the small amount you > plan to spend ($10–$50 in USDC), never with your main holdings. - **EVM_PRIVATE_KEY** (required for Base / Polygon / Arbitrum / World / Avalanche payments) - 0x-prefixed hex string (e.g. `0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80`) - Fund with USDC on Base mainnet (cheapest, fastest, ~$0.0001 gas per call) - One-time cost: ~$10 USDC covers 200+ tool calls - **Hard cap = wallet balance.** A runaway agent loop can spend the funded amount but no more; signing is bounded by USDC available on the chain. - **SVM_PRIVATE_KEY** (optional, for Solana payments) - base58-encoded Solana keypair bytes - Only needed if a tool routes Solana-only **Network whitelist.** The MCP server only signs payments for networks that appear in the API's 402-response `accepts[]` array (currently Base, Polygon, Arbitrum, World Chain, Solana, Algorand, Stellar). Requests routed to any other chain are rejected at the signing layer — your key cannot be tricked into signing for an arbitrary network. **Keys never leave your machine.** They live only in your Claude Desktop config and the MCP process running locally. Payment signing happens on your device; only the signed EIP-712 / SIWS payload travels to Carbon & Cashmere. ### Discovery-only mode (no keys set) If you start the MCP server without `EVM_PRIVATE_KEY` and without `SVM_PRIVATE_KEY`, it runs in **discovery-only mode**: tool registration works, free endpoints work, paid tool invocations surface a 402 error to the agent. Useful for: evaluating the tool catalog, MCP marketplace introspection (Glama, npm scrapers), or running in a CI/test environment without funding a wallet. ## How it works ``` Claude Desktop @carbon-cashmere/x402-mcp api.carbon-cashmere.de | (your machine) (our server) | call get_v1_news | | |------------------------->| GET /v1/news | | |-------------------------------->| | | 402 + PAYMENT-REQUIRED | | |<--------------------------------| | | sign with EVM_PRIVATE_KEY | | | GET /v1/news + PAYMENT-SIG | | |-------------------------------->| | | 200 OK + data | | |<--------------------------------| | formatted data | | |<-------------------------| | ``` Built on official Coinbase x402 v2 protocol. Settlement happens on Base USDC (or your chosen chain). Typical latency: ~2-3 seconds per call (one-shot payment + data). ## Tool count By default, the top 100 tools are exposed — curated server-side by a scoring that combines actual settlement volume, USD revenue, exploration weighting, and description quality (the catalog re-ranks without requiring an npm re-publish). | `X402_TOOL_LIMIT` | What you get | |---|---| | `50` | Minimal footprint — top free + bundles + a few high-revenue endpoints | | `100` (default) | High-revenue tier — adds $10–$50 subscriptions, sponsor tiers, weekly/daily reports, on-chain bundles | | `177` | Everything — adds per-coin specialized routes (vol-regime/{coin}, hurst/{coin}, trend/{coin}, …). Recommended only when your agent knows which coin to query. | Override: ```json "env": { "X402_TOOL_LIMIT": "177" } ``` Why a default cap: too many MCP tools can degrade an agent's tool-selection accuracy. 100 is the empirical sweet spot for Claude 3.5 Sonnet and newer. ## Configuration env | Variable | Required | Default | Description | |---|---|---|---| | `EVM_PRIVATE_KEY` | one of | — | 0x-prefixed EVM key for Base/Polygon/Arbitrum | | `SVM_PRIVATE_KEY` | one of | — | base58 Solana keypair | | `X402_API_BASE` | no | `https://api.carbon-cashmere.de` | API base URL | | `X402_TOOL_LIMIT` | no | `100` | Max tools exposed (1-177) | | `X402_LOG_LEVEL` | no | `info` | `debug \| info \| warn \| error` | ## Security - **Keys never leave your machine.** The MCP server runs locally as a child process of Claude Desktop. - **Pay-per-call cap.** Each call costs $0.003–$0.50. Even a runaway loop is bounded by wallet balance. - **No off-chain credentials.** No API keys. No OAuth. Pure on-chain settlement. - **Open source.** Audit the code yourself: [github.com/CarbonCashmere/x402-mcp](https://github.com/CarbonCashmere/x402-mcp) ## License MIT — see [LICENSE](./LICENSE). ## Links - Carbon & Cashmere API: - x402 protocol: - MCP protocol: