OTSkit

@otskit/mcp

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OpenTimestamps MCP server - stamp, upgrade, and verify Bitcoin timestamps via AI agents.

Exposes a set of tools to any MCP-compatible agent so it can timestamp documents, monitor confirmation status, and verify proofs against the Bitcoin blockchain - all from a conversation.

Note on confirmation times: After stamping, a proof is pending until Bitcoin confirms it. Confirmations typically arrive within ~60 minutes, but can take several hours during network congestion. Use ots-mcp watch or upgrade_timestamp to monitor. A pending proof is not a failed proof.

Install

npm install -g @otskit/mcp

Agent setup

ots-mcp setup claude        # Claude Desktop
ots-mcp setup claude-code   # Claude Code CLI
ots-mcp setup codex         # Codex CLI

Each command writes the MCP entry into the agent's config file, makes a .bak backup if the file already exists, and skips if ots-mcp is already configured. Restart the agent afterwards to apply the changes.

CLI commands

Command	Description
ots-mcp serve	Start the MCP server (stdio transport)
ots-mcp stamp <sha256>	Stamp a SHA-256 hash against Bitcoin calendars
ots-mcp upgrade <id>	Check if a pending stamp has been confirmed
ots-mcp verify <id>	Verify a stamp against Bitcoin
ots-mcp list [status]	List stamps (pending / confirmed / failed)
ots-mcp watch [minutes]	Monitor pending stamps and attempt due upgrades (default: 30 min, minimum: 15 min)
ots-mcp check-pending	Run one upgrade pass over all pending stamps
ots-mcp scheduler install|remove|status	Manage OS-level scheduler for auto-upgrades
ots-mcp backup [dest]	Backup the SQLite database
ots-mcp setup <claude|claude-code|codex>	Configure MCP for an agent

MCP tools exposed to agents

Tool	Description
create_timestamp	Stamp a SHA-256 hash against 4 public OTS calendars
upgrade_timestamp	Check if a pending stamp has been confirmed in Bitcoin
verify_timestamp	Verify a stamp - proves hash existed before a given Bitcoin block
verify_external_proof	Verify a whitelisted local file against its external .ots proof, without changing the local stamp store
inspect_timestamp	Inspect a stored proof file without network calls
list_pending	List stamps with status, retry count, and filters
watch	Open a terminal window monitoring pending stamps and attempting due upgrades
hash_file	Compute the SHA-256 of a local file and return it as a 64-char hex string (no network calls)
stamp_file	Compute SHA-256 of a local file and stamp it on Bitcoin in one step

Data directory

All data is stored in ~/.ots-mcp/:

~/.ots-mcp/
  ots-mcp.db       # SQLite database (stamps, proof files)
  config.json      # Optional config overrides
  ots-mcp.log      # Log file

Configuration

Create ~/.ots-mcp/config.json to override defaults:

{
  "stamp_enabled": true,
  "scheduler_interval_minutes": 30,
  "retry_max_attempts": 20,
  "calendar_timeout_ms": 10000,
  "calendars": [
    "https://alice.btc.calendar.opentimestamps.org",
    "https://bob.btc.calendar.opentimestamps.org",
    "https://finney.calendar.eternitywall.com",
    "https://btc.calendar.catallaxy.com"
  ]
}

Development

npm run build    # production build
npm run dev      # watch mode
npm test         # run tests

Dependencies

• @otskit/client - OTS calendar client (brings in @otskit/core, the protocol engine)
• @modelcontextprotocol/sdk - MCP SDK
• node-sqlite3-wasm - local database (pure WASM, no native compilation)

Requires Node.js >= 20.