Barker MCP Server — Stablecoin Yield for AI Agents

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.

Powered by Barker — Yield Primitive for the Agent Economy. Every agent touching stablecoins eventually plugs in.

接入 Agent 经济的稳定币收益底座 → barker.money

Connect (remote MCP)

The hosted server is a streamable-http MCP endpoint — stateless, no signup, no API key. Payment happens per call via x402 (see Payment).

Endpoint:  https://mcp.barker.money/mcp
Registry:  money.barker/stablecoin-yield   (Official MCP Registry)
Transport: streamable-http (stateless)

Claude Code

claude mcp add --transport http barker https://mcp.barker.money/mcp

Hermes Agent — add to ~/.hermes/config.yaml (takes effect in new sessions):

mcp_servers:
  barker:
    url: "https://mcp.barker.money/mcp"

Cursor / Cline / any MCP host — add to your MCP config:

{
  "mcpServers": {
    "barker": {
      "type": "streamable-http",
      "url": "https://mcp.barker.money/mcp"
    }
  }
}

Smoke test from a terminal (no client needed):

curl -X POST https://mcp.barker.money/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Tools

11 tools in three layers. Prices are per call, settled via x402.

Data

Judgment

Execution (non-custodial)

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.

Payment (x402)

Calling 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.

Facilitators: OKX · Coinbase CDP · Circle Gateway
Settlement:   USDT0 / USDC on X Layer, Base, Ethereum, Polygon, Arbitrum

Full working buyer — pay → quote → verify → sign → broadcast → confirm shares:

npm i viem
read -rs PRIVATE_KEY && export PRIVATE_KEY
node examples/x402-execution-buyer.mjs
unset PRIVATE_KEY

See examples/x402-execution-buyer.mjs — ~200 lines, copy the safety checks into your own agent.

Self-host (stdio)

⚠️ 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.

# Register with Claude Code (user scope, persists across sessions)
claude mcp add -s user barker -- npx -y -p @barkermoney/skills barker-mcp

Then restart Claude Code. Three tools become available:

Smoke test outside of an agent host:

npx -p @barkermoney/skills barker-mcp
# speaks MCP over stdio; pipe JSON-RPC frames to interact

Agent Skill Suite

10 ready-made skills that call the MCP tools with tuned prompts, triggers and guardrails.

One-line install

# Install all 10 skills into ~/.claude/skills/
npx @barkermoney/skills install --all

# Or pick specific ones
npx @barkermoney/skills install stablecoin-yield-radar yield-strategy-advisor

# Other commands
npx @barkermoney/skills list             # show bundled + installed
npx @barkermoney/skills update           # re-install latest of currently installed
npx @barkermoney/skills remove <name>    # uninstall one
npx @barkermoney/skills --help           # full help

Then restart Claude Code (or your agent runtime) to activate. Override the install dir with --target <dir> or $BARKER_SKILLS_DIR.

Updating often? Install the CLI globally so you can drop the npx prefix:

npm install -g @barkermoney/skills
skills install --all     # then from any directory
skills update            # later, pull latest skill content

Hermes Agent

Skills in this repo follow the agentskills.io open standard, so they install into Hermes Agent as-is:

# Flagship skill straight from this repo (repeat for any skill under ./skills):
hermes skills install https://raw.githubusercontent.com/YBSbarker/barker-stablecoin-skills/main/skills/stablecoin-yield-radar/SKILL.md --name stablecoin-yield-radar
hermes skills install https://raw.githubusercontent.com/YBSbarker/barker-stablecoin-skills/main/skills/yield-strategy-advisor/SKILL.md --name yield-strategy-advisor

# Or install the whole suite manually:
git clone https://github.com/YBSbarker/barker-stablecoin-skills.git
cp -r barker-stablecoin-skills/skills/* ~/.hermes/skills/

Skills take effect in new Hermes sessions. Pair them with the remote MCP endpoint (see Connect) 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.

Other install channels

• OKX Wallet Plugin Store: npx skills add okx/plugin-store --skill <skill-name>
• Anthropic Plugin Marketplace: each skill ships .claude-plugin/plugin.json, compatible with the Claude Code plugin marketplace
• Manual: git clone https://github.com/YBSbarker/barker-stablecoin-skills.git && cp -r barker-stablecoin-skills/skills/<skill-name> ~/.claude/skills/

The skills

Access model & security posture

• Authentication / payment: x402 settlement on an HTTP 402 challenge (e.g. via an OKX OnchainOS or wallet payment skill).
• Abuse model: x402 payment gate + edge DDoS protection in front.
• 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).
• Data returned: Public yield / market / TVL figures only. Sensitivity equivalent to public market-data APIs such as CoinGecko or DeFiLlama.
• 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.

Response shape & units

All 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.

Agent discovery: https://api.barker.money/llms.txt

FAQ

Q: How often is the data updated? A: Real-time. The yield index reflects live stablecoin yield data.

Q: Do I need an API key? A: No. Agents call the barker_* tools via the remote MCP — payment is per call via x402, no account or key required.

Q: What stablecoins are covered? A: 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.

Q: What chains are supported? A: 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.

Q: Is this financial advice? A: No. All skills provide educational information only, not financial advice. Always DYOR.

Q: Where can I find the best stablecoin yields? A: Use the stablecoin-yield-radar skill or visit barker.money for the full interactive yield map.

Q: How does Barker compare to DeFiLlama or CoinGecko? A: 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.

About Barker

Barker 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.

• Website: barker.money
• Remote MCP: https://mcp.barker.money/mcp
• Agent discovery: https://api.barker.money/llms.txt (public)

Author & Maintainer Disclosure

• Project: Barker — Yield Primitive for the Agent Economy (barker.money)
• GitHub org: YBSbarker (controlled by the Barker team)
• Submitting committers: zuoyeweb3 (founder), royrzguo (engineering) — both authorized Barker team members
• Contact: partner@barker.money

License

MIT © 2026 Barker