Wraps the live FairSeal Verifiable Entropy API (https://api.fairseal.io) as MCP tools over stdio. Every game outcome is provably fair (commitment-before-entropy

VDF) and independently verifiable — offline, or at verify.fairseal.io.

Install & Run

npx @fairseal/mcp-server

Or add to your MCP client config (Claude Desktop, etc.):

{
  "mcpServers": {
    "fairseal": {
      "command": "npx",
      "args": ["-y", "@fairseal/mcp-server"]
    }
  }
}

Quickstart (60 seconds)

Every random decision your agent makes, from now on, comes with a receipt that any third party can verify. Three paste-and-go paths, all tested against the live API (no key required):

MCP client — local stdio config above, or the hosted endpoint with no local process: examples/claude-desktop-remote-config.json (Claude Code: claude mcp add --transport http fairseal https://api.fairseal.io/mcp)
OpenAI / LangChain function calling — examples/openai_function_calling.py: stdlib-only tools + verify chain (server replay plus local HMAC-SHA256 recompute, so you never take the server's word for it)
curl — examples/curl-60s-demo.sh: roll dice with your own seed → receipt → double verification → shareable proof link at verify.fairseal.io

Full walkthrough: QUICKSTART.md

Tools

Read-only:

Tool	Description
`fairseal_entropy`	Raw verifiable entropy from the latest resolved VDF epoch
`fairseal_games_catalog`	Game catalog (sicbo, dice, gacha, slots) with bet types
`fairseal_stats`	Entropy engine statistics
`fairseal_recent_games`	Recently resolved games (find game_ids to verify)
`fairseal_game_result`	Poll a game result by game_id
`fairseal_verify_game`	Verify fairness of a completed game (VDF proof + replay steps)

Write (live API, play money):

Tool	Description
`fairseal_rng_generate`	Request raw verifiable RNG (resolves next VDF epoch, ~5s)
`fairseal_sicbo_bet`	Three-dice Sic Bo bet
`fairseal_dice_bet`	Two-dice bet (exact/over7/under7/odd/even)
`fairseal_gacha_pull`	Weighted loot-box pull (standard/premium pool)
`fairseal_slots_spin`	5-reel 3-row slots with wild substitution

Preview (local stub, no chain writes):

Tool	Description
`fairseal_anchor_submit`	Preview of Anchor API v2 — queue a SHA-256 hash for Merkle-batch anchoring to Base
`fairseal_anchor_status`	Preview of anchor lifecycle: queued → batched → anchored

Configuration (env vars)

Variable	Default	Notes
`FAIRSEAL_API_URL`	`https://api.fairseal.io`	Upstream API base URL
`FAIRSEAL_API_KEY`	(none)	Sent as `Authorization: Bearer` header. The live API currently requires no auth; the key is plumbed through for forward compatibility — any placeholder works today.
`FAIRSEAL_TIMEOUT_MS`	`15000`	Per-request timeout

What FairSeal Proves

A commitment existed before an externally verifiable anchor point (Base block)
Selection outcomes are mathematically independent of operator will
Receipts have not been modified since creation
Randomness is authentic (VDF verified)

FairSeal issues graduated verification evidence (full taxonomy forthcoming) and is explicit about limits: it does not prove that a claimed execution occurred or that input data was authentic — those require attested execution / independent input validation (future work).