pegcheck-mcp

A read-only MCP server that checks whether a Robinhood Chain Stock Token is currently trading at a fair price relative to the real-world stock it represents — designed to be called by an AI agent, right before it trades, not read off a dashboard by a human.

✅ Verdict: FAIR (deviation: 0.11%)

The problem

Robinhood Chain's Stock Tokens are self-custodiable ERC-20s that track real stocks and trade 24/7 on onchain DEXs. Real stock markets are only open ~6.5 hours a day, 5 days a week. Outside those hours there's no active market to arbitrage the token price back to fair value, so it can drift.

An AI agent trading these tokens directly onchain — holding a wallet key and swapping against a DEX pool — has no built-in way to know if the price it's about to pay is trustworthy. Every existing tool that surfaces this gap (dashboards, Telegram alert bots, trading terminals) is built for a human to look at. None of them are built to be called by an agent mid-decision.

The solution

One focused MCP tool: check_stock_token_price.

Give it a ticker. It returns a structured, session-aware verdict an agent can act on — before it signs a trade, whether that trade goes through Robinhood's own Trading MCP or directly against an onchain DEX.

{
  "symbol": "AAPL",
  "onchain": { "priceUsd": 310.32, "method": "liquidity-weighted-average", "poolsUsed": 10 },
  "reference": { "tokenEquivalentPriceUsd": 309.99, "isTradingHalt": false },
  "deviation": { "pct": 0.11, "direction": "premium" },
  "marketSession": { "state": "weekend" },
  "verdict": "fair",
  "warnings": []
}

This server is read-only. It never holds a private key, never signs a transaction, and never places a trade.

How it works

Two independent data sources, compared:

1. Onchain price — every indexed Robinhood Chain pool for the token, from DexScreener's public API, filtered to pools quoted in a stable reference asset (USDG/USDC) with at least $500 of liquidity, combined into a liquidity-weighted average (so one deep pool dominates over several shallow, noisy ones). Falls back to the single deepest pool — flagged as low-confidence — if nothing passes the filter.
2. Reference price — Robinhood's own public Stock Token API (/rhj/prices/{symbol}), which reports the raw underlying-equity bid/ask. This is scaled by the token's current ERC-8056 multiplier (from /rhj/assets) to get the token-equivalent fair price, since dividends are reinvested into the multiplier rather than paid out in cash.

The deviation between the two is compared against a threshold table that depends on the current US market session (regular, pre-market, after-hours, weekend, holiday, closed), computed locally with no external dependency — a 2% gap on a Saturday night is expected; the same gap at 11am on a Tuesday is not. Session detection includes a full NYSE holiday calendar, computed algorithmically (nth-weekday-of-month rules, an Easter calculation for Good Friday, and the standard weekend-observance shift) rather than fetched from any external API, so it works for any year with no network dependency, no API key, and no static file to go stale. Verified against NYSE's officially published 2026-2028 calendar in test/nyseHolidays.test.ts. See src/config.ts for the exact thresholds and src/nyseHolidays.ts for the holiday rules.

Install & run

git clone https://github.com/kushal613/pegcheck-mcp.git
cd pegcheck-mcp
npm install
npm run build

No API keys, no .env file, no wallet — every data source used is a free, public, keyless API.

Try it from the terminal

npm run check -- AAPL
npm run check -- TSLA

Connect it to an MCP client

Claude Desktop / Claude Code (claude_desktop_config.json or .mcp.json):

{
  "mcpServers": {
    "pegcheck": {
      "command": "node",
      "args": ["/absolute/path/to/pegcheck-mcp/dist/index.js"]
    }
  }
}

Cursor (.cursor/mcp.json): same shape as above.

Once connected, ask your agent: "Before you buy any TSLA stock token, check pegcheck to see if the price is fair right now."

Tool reference

check_stock_token_price

Field	Type	Description
symbol (input)	string	Ticker, e.g. "AAPL".
onchain.priceUsd	number | null	Liquidity-weighted onchain price.
onchain.method	string	liquidity-weighted-average, deepest-pool (low confidence), or none.
reference.tokenEquivalentPriceUsd	number | null	Real stock mid-price, scaled by the corporate-action multiplier.
deviation.pct	number | null	Signed % deviation, onchain vs. reference.
marketSession.state	string	regular | pre-market | after-hours | weekend | holiday | closed.
marketSession.holidayName	string | null	e.g. "Thanksgiving Day", when state is "holiday".
verdict	string	fair | caution | unreliable | no_liquidity | unknown_symbol.
warnings	string[]	Human-readable caveats (stale quote, trading halt, low-confidence pool, etc.).

Architecture

src/
  config.ts        Every tunable threshold, in one place
  types.ts         Shared types for the whole pipeline
  http.ts          Fetch wrapper with timeout + consistent errors
  robinhoodApi.ts  Reference leg: /rhj/assets + /rhj/prices (Robinhood's own APIs)
  dexscreener.ts   Onchain leg: liquidity-weighted price across Robinhood Chain pools
  marketSession.ts Local US-market-session calculation (no external dependency)
  nyseHolidays.ts  Algorithmic NYSE holiday calendar (no external dependency)
  pegCheck.ts       Combines both legs into one PegCheckResult
  server.ts        MCP tool registration
  index.ts         stdio entrypoint
  cli.ts           Standalone terminal usage (no MCP client needed)
scripts/
  smoke-test.mjs   End-to-end MCP protocol handshake test (initialize -> tools/list -> tools/call)

Known limitations (v0.1)

• No early-close handling. NYSE's 1:00 PM closes (day after Thanksgiving, a weekday Christmas Eve) are not modeled as a distinct session — those afternoons will still report after-hours/closed a few hours later than the real early close. Full-day holiday closures are fully covered.
• No venue-specific slippage estimate. This reports the aggregate liquidity-weighted price, not "what would my $500 trade cost against this specific pool." That's a deliberate v0.1 scope boundary (a natural v0.2: an advanced mode that takes a trade size and a specific pool/venue and estimates price impact).
• DexScreener coverage dependency. If DexScreener hasn't indexed a very new pool yet, onchain.method will be "none" and the verdict will be no_liquidity. This is a "fail loud," not a silent wrong answer.
• Not a substitute for due diligence. See the disclaimer below.

Disclaimer

This project is not affiliated with or endorsed by Robinhood. It is an independent, informational tool. Data is sourced from Robinhood's public APIs and DexScreener's public API and may be delayed, incomplete, or inaccurate. Nothing here is financial advice. This server cannot place trades and holds no funds or keys.

License

MIT — see LICENSE.