{
  "markdown": "# Barker MCP Server — Stablecoin Yield for AI Agents\n\n> **Barker — remote MCP server for real-time stablecoin yield: live APY index, AI yield advisor, risk signals, and non-custodial deposit/redeem execution — 11 tools, x402 pay-per-call. Plus the official Barker agent skill suite.**\n\n[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)\n[![MCP Registry](https://img.shields.io/badge/MCP_Registry-money.barker%2Fstablecoin--yield-blue.svg)](https://registry.modelcontextprotocol.io)\n[![Payment: x402](https://img.shields.io/badge/Payment-x402_pay--per--call-green.svg)](https://mcp.barker.money)\n\nPowered by [**Barker — Yield Primitive for the Agent Economy**](https://barker.money). Every agent touching stablecoins eventually plugs in.\n\n接入 Agent 经济的稳定币收益底座 → [barker.money](https://barker.money)\n\n---\n\n## Connect (remote MCP)\n\nThe hosted server is a **streamable-http MCP endpoint** — stateless, no signup, no API key. Payment happens per call via x402 (see [Payment](#payment-x402)).\n\n```\nEndpoint:  https://mcp.barker.money/mcp\nRegistry:  money.barker/stablecoin-yield   (Official MCP Registry)\nTransport: streamable-http (stateless)\n```\n\n**Claude Code**\n\n```bash\nclaude mcp add --transport http barker https://mcp.barker.money/mcp\n```\n\n**Hermes Agent** — add to `~/.hermes/config.yaml` (takes effect in new sessions):\n\n```yaml\nmcp_servers:\n  barker:\n    url: \"https://mcp.barker.money/mcp\"\n```\n\n**Cursor / Cline / any MCP host** — add to your MCP config:\n\n```json\n{\n  \"mcpServers\": {\n    \"barker\": {\n      \"type\": \"streamable-http\",\n      \"url\": \"https://mcp.barker.money/mcp\"\n    }\n  }\n}\n```\n\n**Smoke test from a terminal** (no client needed):\n\n```bash\ncurl -X POST https://mcp.barker.money/mcp \\\n  -H 'Content-Type: application/json' \\\n  -H 'Accept: application/json, text/event-stream' \\\n  -d '{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"tools/list\"}'\n```\n\n## Tools\n\n11 tools in three layers. Prices are per call, settled via x402.\n\n**Data**\n\n| Tool | What it returns | Price |\n|------|-----------------|-------|\n| `barker_defi_vaults` | Ranked stablecoin yield pools (APY, TVL, protocol, chain, asset) | $0.001 |\n| `barker_market_overview` | Total market cap, yield-bearing cap, asset/chain distribution | $0.001 |\n| `barker_market_trend` | Historical APY trend (7–180 days) vs US Treasury benchmark | $0.001 |\n| `barker_pool_search` | Search the yield index by asset, chain, protocol or keyword | $0.001 |\n\n**Judgment**\n\n| Tool | What it returns | Price |\n|------|-----------------|-------|\n| `barker_yield_advisor` | Ranked top-N picks with data-derived reasons and risk flags | $0.03 |\n| `barker_pool_detail` | Full single-pool dossier: APY components, TVL, terms, rewards | $0.005 |\n| `barker_pool_history` | Historical APY / TVL series for one pool | $0.005 |\n| `barker_crosschain_routes` | Cross-chain routing options between pools | $0.01 |\n\n**Execution (non-custodial)**\n\n| Tool | What it returns | Price |\n|------|-----------------|-------|\n| `barker_executable_pools` | Vaults an agent can act on right now — every row guaranteed quotable | $0.01 |\n| `barker_execution_quote` | Unsigned, ready-to-sign deposit/redeem tx (`{chainId, to, data, value}`) + route + risk | $0.05 |\n| `barker_vault_position` | On-chain read of a wallet's ERC-4626 vault position | $0.001 |\n\n**Barker never broadcasts and never holds funds.** The agent verifies the returned calldata (`calldata_amount_base_units` enables byte-level verification) and the user's own wallet signs. Vault shares always go to the signer — `receiver` is not a parameter. Same-chain only.\n\n## Payment (x402)\n\nCalling a tool without payment returns an HTTP 402 challenge. Settle it (e.g. via an OKX OnchainOS or wallet payment skill, or any x402 buyer client) and retry with the payment header.\n\n```\nFacilitators: OKX · Coinbase CDP · Circle Gateway\nSettlement:   USDT0 / USDC on X Layer, Base, Ethereum, Polygon, Arbitrum\n```\n\nFull working buyer — pay → quote → verify → sign → broadcast → confirm shares:\n\n```bash\nnpm i viem\nread -rs PRIVATE_KEY && export PRIVATE_KEY\nnode examples/x402-execution-buyer.mjs\nunset PRIVATE_KEY\n```\n\nSee [`examples/x402-execution-buyer.mjs`](examples/x402-execution-buyer.mjs) — ~200 lines, copy the safety checks into your own agent.\n\n## Self-host (stdio)\n\n> ⚠️ **Self-host only.** The bundled `barker-mcp` stdio server wraps the resource endpoints as local tools, for operators self-hosting against their own `BARKER_API_BASE`. Barker's hosted tools are served via the remote MCP above.\n\n```bash\n# Register with Claude Code (user scope, persists across sessions)\nclaude mcp add -s user barker -- npx -y -p @barkermoney/skills barker-mcp\n```\n\nThen restart Claude Code. Three tools become available:\n\n| Tool | Wraps | Use for |\n|------|-------|---------|\n| `barker_defi_vaults` | `/defi/vaults` | \"best USDC yield\", \"Aave vs Morpho\", filter by asset/chain/sort/limit |\n| `barker_market_overview` | `/market/overview` | total cap, yield-bearing cap, asset/chain distribution |\n| `barker_market_trend` | `/market/trend` | 7–180 day APY trend vs US Treasury benchmark |\n\nSmoke test outside of an agent host:\n\n```bash\nnpx -p @barkermoney/skills barker-mcp\n# speaks MCP over stdio; pipe JSON-RPC frames to interact\n```\n\n---\n\n## Agent Skill Suite\n\n10 ready-made skills that call the MCP tools with tuned prompts, triggers and guardrails.\n\n### One-line install\n\n```bash\n# Install all 10 skills into ~/.claude/skills/\nnpx @barkermoney/skills install --all\n\n# Or pick specific ones\nnpx @barkermoney/skills install stablecoin-yield-radar yield-strategy-advisor\n\n# Other commands\nnpx @barkermoney/skills list             # show bundled + installed\nnpx @barkermoney/skills update           # re-install latest of currently installed\nnpx @barkermoney/skills remove <name>    # uninstall one\nnpx @barkermoney/skills --help           # full help\n```\n\nThen restart Claude Code (or your agent runtime) to activate. Override the install dir with `--target <dir>` or `$BARKER_SKILLS_DIR`.\n\n**Updating often?** Install the CLI globally so you can drop the `npx` prefix:\n\n```bash\nnpm install -g @barkermoney/skills\nskills install --all     # then from any directory\nskills update            # later, pull latest skill content\n```\n\n### Hermes Agent\n\nSkills in this repo follow the [agentskills.io](https://agentskills.io) open standard, so they install into [Hermes Agent](https://github.com/NousResearch/hermes-agent) as-is:\n\n```bash\n# Flagship skill straight from this repo (repeat for any skill under ./skills):\nhermes skills install https://raw.githubusercontent.com/barkermoney/barker-mcp/main/skills/stablecoin-yield-radar/SKILL.md --name stablecoin-yield-radar\nhermes skills install https://raw.githubusercontent.com/barkermoney/barker-mcp/main/skills/yield-strategy-advisor/SKILL.md --name yield-strategy-advisor\n\n# Or install the whole suite manually:\ngit clone https://github.com/barkermoney/barker-mcp.git\ncp -r barker-mcp/skills/* ~/.hermes/skills/\n```\n\nSkills take effect in new Hermes sessions. Pair them with the remote MCP endpoint (see [Connect](#connect-remote-mcp)) so tool calls resolve. Hermes has no built-in payments: route the x402 pay-per-call through an x402-capable payment skill, funded from a **dedicated low-balance payments wallet** — never your main wallet key. `tools/list` and discovery stay free.\n\n### Other install channels\n\n- **OKX Wallet Plugin Store**: `npx skills add okx/plugin-store --skill <skill-name>`\n- **Anthropic Plugin Marketplace**: each skill ships `.claude-plugin/plugin.json`, compatible with the Claude Code plugin marketplace\n- **Manual**: `git clone https://github.com/barkermoney/barker-mcp.git && cp -r barker-mcp/skills/<skill-name> ~/.claude/skills/`\n\n### The skills\n\n| Skill | What It Does | Data Source | Key Triggers |\n|-------|-------------|-------------|-------------|\n| [stablecoin-yield-radar](./skills/stablecoin-yield-radar/) | Real-time stablecoin APY rankings | `barker_defi_vaults` | \"best stablecoin yield\", \"where to earn on USDC\" |\n| [stablecoin-market-brief](./skills/stablecoin-market-brief/) | Market overview: cap, distribution, APY trends vs US Treasury | `barker_market_overview` + `barker_market_trend` | \"stablecoin market cap\", \"USDT market share\" |\n| [stablecoin-risk-check](./skills/stablecoin-risk-check/) | Safety assessment: depeg history, reserves, audit status | Curated knowledge base | \"is USDT safe\", \"stablecoin comparison\" |\n| [yield-strategy-advisor](./skills/yield-strategy-advisor/) | Personalized allocation by risk tolerance and capital size | `barker_defi_vaults` | \"yield strategy\", \"how to earn on stablecoins\" |\n| [stablecoin-depeg-monitor](./skills/stablecoin-depeg-monitor/) | Peg stability monitoring + historical depeg database | `barker_market_overview` + curated history | \"depeg alert\", \"is my stablecoin safe right now\" |\n| [stablecoin-yield-vs-tradfi](./skills/stablecoin-yield-vs-tradfi/) | Stablecoin yields vs bank savings, Treasury, money market | `barker_market_trend` | \"stablecoin vs savings account\", \"DeFi vs treasury\" |\n| [stablecoin-chain-explorer](./skills/stablecoin-chain-explorer/) | TVL distribution and best yields by blockchain | `barker_market_overview` + `barker_defi_vaults` | \"which chain for stablecoins\", \"Arbitrum stablecoin APY\" |\n| [agent-payment-stats](./skills/agent-payment-stats/) | Cross-protocol agent-economy payment metrics (x402 real vs nominal, top sellers) | `barker_agent_payment_stats` | \"x402 volume\", \"agent economy metrics\" |\n| [stablecoin-treasury-yield](./skills/stablecoin-treasury-yield/) | B2B treasury & idle-balance yield: quantify idle float, run the $10 probe, map integration | `barker_defi_vaults` + execution tools | \"idle balance\", \"treasury yield\", \"沉淀资金\" |\n| [stablecoin-tvl-boost](./skills/stablecoin-tvl-boost/) | TVL growth for protocols: boost campaigns & launchpools (40k+ users, on-chain attribution) | `barker_market_overview` + `barker_defi_vaults` | \"grow TVL\", \"launchpool\" |\n\n---\n\n## Access model & security posture\n\n- **Authentication / payment**: x402 settlement on an HTTP 402 challenge (e.g. via an OKX OnchainOS or wallet payment skill).\n- **Abuse model**: x402 payment gate + edge DDoS protection in front.\n- **Data scope sent to the API**: Only public market parameters — stablecoin symbol, chain name, sort/limit. **No** wallet addresses, balances, signatures, private keys, or PII are transmitted by any skill in this suite (the only exception: `barker_vault_position` reads a wallet's public on-chain vault balance for an address the agent explicitly passes).\n- **Data returned**: Public yield / market / TVL figures only. Sensitivity equivalent to public market-data APIs such as CoinGecko or DeFiLlama.\n- **External data boundary**: Every SKILL.md in this suite includes a `## Security: External Data Boundary` section instructing consuming LLMs to treat all API response strings as untrusted data, not instructions.\n\n### Response shape & units\n\nAll responses are JSON with `{ success, data, ... }`. APY and `share_pct` fields are **decimals** (`0.0523` = 5.23%, `0.4250` = 42.5%) — multiply by 100 for display.\n\nAgent discovery: [`https://api.barker.money/llms.txt`](https://api.barker.money/llms.txt)\n\n---\n\n## FAQ\n\n**Q: How often is the data updated?**\nA: Real-time. The yield index reflects live stablecoin yield data.\n\n**Q: Do I need an API key?**\nA: No. Agents call the `barker_*` tools via the remote MCP — payment is per call via x402, no account or key required.\n\n**Q: What stablecoins are covered?**\nA: All stablecoins on the market — USDT, USDC, DAI, USDS, USDe, sUSDe, FDUSD, GHO, crvUSD, PYUSD, sDAI, frxUSD, TUSD, BUSD, LUSD, DOLA, MIM, FRAX, USDs, USDX, RLUSD, USDY, BUIDL, and more. If a stablecoin exists, Barker covers it.\n\n**Q: What chains are supported?**\nA: All chains — Ethereum, BSC, Arbitrum, Base, Polygon, Optimism, Avalanche, Solana, Sui, Aptos, Sei, Mantle, Scroll, zkSync, Linea, Blast, Mode, Manta, and more. Barker has the most comprehensive multi-chain coverage in the market.\n\n**Q: Is this financial advice?**\nA: No. All skills provide educational information only, not financial advice. Always DYOR.\n\n**Q: Where can I find the best stablecoin yields?**\nA: Use the `stablecoin-yield-radar` skill or visit [barker.money](https://barker.money) for the full interactive yield map.\n\n**Q: How does Barker compare to DeFiLlama or CoinGecko?**\nA: Barker is **stablecoin-only** and indexes real-time stablecoin yield in a single index. DeFiLlama focuses on on-chain TVL; CoinGecko focuses on token prices. Barker is the specialized yield index for stablecoins.\n\n---\n\n## About Barker\n\n[Barker](https://barker.money) is the **Yield Primitive for the Agent Economy** — the default routing layer that any agent (or app, or human) calls when it needs to answer \"where should this stablecoin sit?\". We index real-time stablecoin yield, surfaced as a map for humans browsing and as MCP / agent-callable endpoints for autonomous agents. Stablecoins only. Agents get a real-time stablecoin yield index, an AI yield advisor, non-custodial execution, and risk signals via the MCP; the interactive map is browsable by humans at [barker.money](https://barker.money).\n\n- Website: [barker.money](https://barker.money)\n- Remote MCP: `https://mcp.barker.money/mcp`\n- Agent discovery: `https://api.barker.money/llms.txt` (public)\n\n## Author & Maintainer Disclosure\n\n- **Project**: Barker — Yield Primitive for the Agent Economy ([barker.money](https://barker.money))\n- **GitHub org**: [barkermoney](https://github.com/barkermoney) (controlled by the Barker team)\n- **Submitting committers**: `zuoyeweb3` (founder), `royrzguo` (engineering) — both authorized Barker team members\n- **Contact**: partner@barker.money\n\n## License\n\nMIT © 2026 [Barker](https://barker.money)\n",
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