Short answer - Even if prompts are signed off-chain, a bloc…

Short answer
- Even if prompts are signed off-chain, a blockchain still matters as the root of trust, revocation, shared discoverability, and audit anchor:
- Root-of-truth PKI: who owns/controls the agent and which keys/capabilities are valid.
- Revocation and rotation: session keys can be granted/revoked without trusting any single server.
- Third-party verification: tools/services can independently read the same registry to enforce capabilities.
- Auditability: you can periodically anchor hashes of accepted prompts/results for tamper-evident logs.