@treeship/mcp

Drop-in Treeship attestation for MCP tool calls. One import change, every tool call gets a signed receipt.

Install

npm install @treeship/mcp

Requires the treeship CLI binary in PATH:

curl -fsSL treeship.dev/install | sh
treeship init

Usage

Change one import. Everything else stays the same.

// Before (no attestation):
import { Client } from '@modelcontextprotocol/sdk'

// After (every tool call attested):
import { Client } from '@treeship/mcp'

const client = new Client({ name: 'my-agent', version: '1.0' }, {})
await client.connect(transport)

const result = await client.callTool({
  name: 'brave_search',
  arguments: { query: 'AI safety 2026' }
})

// Treeship metadata attached to result
console.log(result._treeship)
// { intent: 'art_aaa', tool: 'brave_search', actor: 'agent://mcp-my-agent' }

What happens automatically

Every callTool() creates two artifacts:

1. Intent (awaited before the call) -- proves what was about to happen
2. Receipt (fire-and-forget after the call) -- proves what happened

Both are signed with Ed25519, content-addressed, and auto-chained.

Environment variables

| Variable | Effect | |----------|--------| | TREESHIP_DISABLE=1 | Full passthrough, zero attestation | | TREESHIP_ACTOR | Override default actor URI | | TREESHIP_APPROVAL_NONCE | Bind all calls to an approval | | TREESHIP_DEBUG=1 | Log attestation failures to stderr |

Design rules

• Treeship errors never fail the underlying tool call
• Only hashes are stored, never raw content
• Intent attestation is awaited (proof of what was about to happen)
• Receipt attestation is fire-and-forget (never blocks response)
• TREESHIP_DISABLE=1 produces zero overhead

License

Apache-2.0