Feature: Cryptographic receipts for agent tool execution (AAR)

Problem

smolagents executes tools on behalf of users — code execution, web search, API calls. Each tool run produces a result but no cryptographic proof that the tool actually ran with those specific inputs and produced that specific output.

For multi-agent systems, enterprise deployments, and agent commerce, verifiable action provenance is becoming a requirement.

Proposal

Integrate Agent Action Receipts (AAR) into the tool execution pipeline:

# Conceptual: receipt-aware tool execution
class VerifiableTool(Tool):
    def forward(self, *args, **kwargs):
        result = super().forward(*args, **kwargs)
        receipt = create_receipt(
            agent_id=self.agent.name,
            action={'tool': self.name, 'args_hash': sha256(str(args))},
            output_hash=sha256(str(result)),
        )
        return result, receipt

Each agent run produces a receipt chain — verifiable by any party with the agent's public key.

What AAR provides

• Ed25519 signatures over canonicalized JSON per action
• SHA-256 input/output hashing (verifiable without exposing raw data)
• Receipt chaining across multi-step tool use
• Compatible with Mastercard Verifiable Intent and x402 (Coinbase)

SDK

TypeScript: npm install botindex-aar (live, MIT) Python: in development

• Spec: https://github.com/Cyberweasel777/agent-action-receipt-spec
• Landing: https://aar.botindex.dev