barker-mcp

Barker MCP was developed by the Barker team and is positioned as the "yield primitive of the agent economy," providing AI agents with real-time stablecoin yield-related capabilities. The project offers both a remote MCP server and an official agent skills suite.

Purpose and Positioning Barker focuses on the stablecoin yield space, integrating real-time stablecoin yield data into a single index for AI agents (as well as applications or humans) to call upon when they need to answer "where should this stablecoin go." Its interactive yield map is available for humans to browse at barker.money, while capabilities for autonomous agents are provided through MCP / agent-callable endpoints.

Connection Method (Remote MCP) The hosted server is a streamable-http MCP endpoint that is stateless, requires no registration and no API key, with payment settled per call via x402. It can be added to Hermes Agent's ~/.hermes/config.yaml (takes effect in a new session), or included in the MCP configuration of Cursor, Cline, and other MCP hosts. It also supports smoke testing from the terminal without a client.

Main Capabilities (Tool Tiers) The server provides three tiers totaling 12 tools (the documentation elsewhere states "11 tools"), priced per call and settled via x402. These include:

• Real-time APY yield index
• AI yield advisor
• Risk signals
• Non-custodial deposit/redemption execution quotes

Execution Mechanism (Non-Custodial) Barker never broadcasts transactions and never holds funds. The agent verifies the returned calldata (calldata_amount_base_units supports byte-level verification), which is signed by the user's own wallet. Vault shares are always sent to the signer—receiver is not a parameter. Only same-chain operations are supported. If a tool is called without payment, it returns an HTTP 402 challenge; after completing settlement (for example, via OKX OnchainOS or a wallet payment skill, or any x402 buyer client), retry with the payment header.

Self-Hosting (stdio) The project includes a barker-mcp stdio server that wraps the resource endpoints as local tools, aimed at operators who self-host and point to their own BARKER_API_BASE. It should be noted that this method is for self-hosting only. After configuration, restart Claude Code and three tools will be available; smoke testing can also be done outside the agent host.Barker's hosted tools are provided through the above remote MCP.

Agent Skills Suite Includes 10 ready-made skills that invoke MCP tools through tuned prompts, triggers, and guardrail rules. Supports one-line command installation; after installation, restart Claude Code (or the agent runtime being used) to activate; the installation directory can be overridden via --target <dir> or $BARKER_SKILLS_DIR. If updates are frequent, install the CLI globally to save the npx prefix. The skills follow the agentskills.io open standard and can be installed directly into Hermes Agent, taking effect in a new session. They must be used with the remote MCP endpoint in order for tool calls to resolve. Hermes has no built-in payment: pay-per-use must be routed through an x402-capable payment skill, with funds coming from a dedicated low-balance payment wallet—never use the main wallet key. tools/list and discovery remain free.

Other Installation Channels

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

Model access and security posture

• Authentication/payment: x402 settlement based on HTTP 402 challenges (for example, via OKX OnchainOS or a wallet payment skill).
• Abuse model: x402 payment gate + front-edge DDoS protection.
• Scope of data sent to the API: only public market parameters—stablecoin symbols, chain names, sorting/count limits. No skill in this suite transmits wallet addresses, balances, signatures, private keys, or PII (the only exception: barker_vault_position reads the public on-chain vault balance for the wallet corresponding to the address explicitly passed in by the agent).
• Returned data: only public yield/market/TVL numbers. Sensitivity is equivalent to public market data APIs such as CoinGecko or DeFiLlama.
• External data boundary: every SKILL.md in the suite includes a "## Security: External Data Boundary" section, instructing the consuming LLM to treat all API response strings as untrusted data rather than instructions.

Response structure and units All responses are JSON with the structure { success, data, ... }. APY and share_pct fields are decimals (0.0523 = 5.23%, 0.4250 = 42.5%)—multiply by 100 when displaying.

Frequently asked questions (official notes)

• Data update frequency: real time. The yield index reflects real-time stablecoin yield data.
• Is an API key required: no. Agents call the barker_* tools through the remote MCP and pay per call via x402, with no account or key required.
• Stablecoins covered: all stablecoins in 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. As long as a stablecoin exists, Barker covers it.
• Supported chains: all chains—Ethereum, BSC, Arbitrum, Base, Polygon, Optimism, Avalanche, Solana, Sui, Aptos, Sei, Mantle, Scroll, zkSync, Linea, Blast, Mode, Manta, and more.
• Is this financial advice: no. All skills provide educational information only and do not constitute financial advice. Always do your own research (DYOR).
• Where to find the best stablecoin yields: use the stablecoin-yield-radar skill, or visit barker.money to view the full interactive yield map.
• Comparison with DeFiLlama / CoinGecko: Barker focuses only on stablecoins and indexes real-time stablecoin yields with a single index; DeFiLlama focuses on on-chain TVL, and CoinGecko focuses on token prices.

Use cases Suitable for AI agents and applications that need to query real-time stablecoin yields, obtain yield recommendations, view risk signals, or prepare non-custodial deposit/redemption transactions; also suitable for human users browsing yields through the barker.money interactive map.

Limitations Execution supports same-chain only, and does not broadcast or custody funds; payment is per call and requires x402 settlement capability; self-hosting is only available for stdio scenarios. All information does not constitute financial advice.

Other information Website: barker.money; remote MCP:https://mcp.barker.money/mcp；智能体发现：https://api.barker.money/llms.txt（公开）。作者与维护者披露：项目为 Barker — Yield Primitive for the Agent Economy (barker.money), with the GitHub organization barkermoney (controlled by the Barker team), submitters zuoyeweb3 (founder) and royrzguo (engineering), both authorized members of the Barker team, contact partner@barker.money. License: MIT © 2026 Barker.