orc-seal

Every MCP tool result gets a receipt a stranger can verify. Put orc-seal in front of any MCP server, in any language, with no code changes. Each successful tools/call result carries an Outcome Receipt (ORC v0.1) under result._meta["com.viridisconservation/orc"].

Identity standards say who an agent is. Payment rails say what was paid. A receipt says what was actually delivered, and anyone can check it.

Use it (one line)

In your MCP client config, prefix the server command:

{ "command": "orc-seal",
  "args": ["--issuer", "did:web:yourdomain.com", "--", "npx", "-y", "@you/your-mcp-server"] }

Install: pip install orc-seal (stdlib only, Python ≥ 3.10).

Levels

The registry only ever sees the commitment, digest, salt, profile and tool name. Your outputs and tool arguments never leave the process. Arguments are not in the receipt either; only their SHA-256 is.

Verify

• In a browser: open the receipt's verify.page link (runs locally in the page).
• CLI: orc-seal verify receipt.json
• Python: from orc_seal import verify

Python decorator (optional)

from orc_seal import Sealer, sealed
s = Sealer({"id": "did:web:yourdomain.com"})
@sealed(s)
def quote(kwh: int) -> dict: ...
quote(1000)  # -> {"result": {...}, "orc": {...receipt...}}

Guarantees (tested)

M1 result never changed · M2 every receipt verifies · M3 arguments and outputs never sent · M4 registry failures fail open · M5 deterministic float handling · M6 errors are not sealed · M7 oversized results pass through unsealed · P1 non-tool traffic is byte-identical.

Get a registry key

Email hartjustin6@gmail.com with your issuer id. Design partners get the free tier and help shape ORC v0.2.

Apache-2.0 · Viridis LLC