Give your agent
a tab.

The Opentab MCP server lets any AI agent pay x402 APIs, open a fully backed USDC tab when its wallet is short, settle it on time and read its score, with no human in the loop once the backing is in place. Every tool answers in JSON, and every error comes with the next step to take.

The server runs on your machine with Node 20 or later, straight from this site. Give it a dedicated agent keypair (a Solana JSON keypair file) holding a little SOL for fees and rent, and the USDC it pays APIs with.

{
  "mcpServers": {
    "opentab": {
      "command": "npx",
      "args": ["-y", "https://opentabworld.live/mcp-0.1.1.tgz"],
      "env": {
        "OPENTAB_KEYPAIR": "/Users/you/.config/solana/agent.json"
      }
    }
  }
}

claude mcp add opentab --env OPENTAB_KEYPAIR=$HOME/.config/solana/agent.json -- npx -y https://opentabworld.live/mcp-0.1.1.tgz

Amounts are USDC decimal strings like "25.5". Every tool that sends a transaction also takes dry_run: true to check it and preview the exact amounts without sending, except pay_x402 and settle_tabs.

get_protocol_info   {}
register_agent      {}                                  // the agent's wallet becomes its identity
back_agent          { "amount": "50" }                  // the owner backs from the agent wallet, a sponsor from theirs
get_credit_limit    { "term_days": 8 }
open_tab            { "principal": "5", "term_days": 8, "dry_run": true }
open_tab            { "principal": "5", "term_days": 8, "max_fee": "0.013334" }
pay_x402            { "url": "https://api.example.com/report" }
settle_tabs         {}                                  // after 7 days held, or 6 h before due
get_score           {}

In practice the agent only calls pay_x402: when the wallet is short it opens the smallest tab that covers the call, and it settles open tabs on its own when they are due. A tab backed by the agent’s own wallet repays normally but doesn’t move the score: the score counts tabs someone else backed.

• Borrow past its backing. A tab locks its principal plus its fee from the backing, so the agent can never owe more than someone locked for it.
• Pay past its caps. Each call is capped (0.50 USDC by default, or per API with OPENTAB_HOST_CAPS) and each UTC day too (10 USDC).
• Pay an API you didn’t allow. With OPENTAB_PAY_HOSTS set, other hosts are refused; hosts in OPENTAB_ASK_HOSTS return needs_approval instead of paying, and only hosts in OPENTAB_TAB_HOSTS (when set) may open a tab.
• Follow a stranger’s instructions. What an API answers comes back under untrusted.body: data, never instructions. Redirects aren’t followed.

// on each repayment of a tab backed by someone other than the agent, by its due date + 3 days
held            = min(now - start, due - start)            // capped at the term
dollar_seconds += principal × held
qualified      += 1 if held ≥ 7 days
time_pts  = min(600, ⌊dollar_seconds / 864_000_000_000⌋)   // 1 point per 10 USDC-days
count_pts = min(400, 40 × qualified)                       // 40 per tab held 7+ days
score     = min(1000, time_pts + count_pts)                // a default sets it to 0 for good

Levels are worked out the same way by this site, the check API and the MCP server: Unproven (nothing repaid), Started (one tab repaid), Proven (3 sponsored tabs held 7+ days, 14 days between the first and the latest, never repaid more than 24 h late), Established (Proven, score 500+, 30 days since the first sponsored repayment), and Defaulted. Honest limit: a sponsor is any other wallet, so a second wallet of the same person still counts. It makes a fake record cost money and time; it doesn’t make it impossible.

Before you back, lend to or hire an agent, look it up. One GET returns its score, level, what the next level still needs, and the facts behind them. Any site may call it; answers are cached for 30 seconds.

curl "https://opentabworld.live/api/check?agent=<AGENT_WALLET>"

{
  "agent": "<AGENT_WALLET>",
  "verdict": "repaid",             // "no record" | "no repayments yet" | "repaid" | "defaulted"
  "score": 188,
  "level": "Started",
  "next": [{ "key": "qualified", "have": 1, "need": 3, "met": false }, …],
  "tabs_repaid": 2,
  "sponsored_repaid": 1,
  "late_repayments": 0,
  "open_tab": null,
  "defaulted": false,
  "profile_url": "https://opentabworld.live/agents/<AGENT_WALLET>"
}

Tools return { code, message, hint }: the program’s error name, a plain sentence and the next step.

One Solana program holds the pool, the backing and every tab. Tab accounts are never closed, so the full history stays readable.

Fee: ceil(principal × 100 × term / (10,000 × 30 days)), so a 5 USDC tab for 7 days costs 0.011667 USDC. Split on repayment: 50% lenders, 25% the backer, 25% reserve. The program is upgradeable until it has been audited; the upgrade key is the admin key, and moving it to a multisig is the next step.

• Use a dedicated keypair with only the USDC and SOL the agent needs. Never reuse a wallet that holds anything else.
• The keypair file is read once at startup and is never logged or returned by any tool. Keep it readable only by you.
• Backing is the limit. Lock only what you are comfortable losing if the agent defaults.