Feature: Add financial governance evaluator for agent spend limits

[up2itnow0822]

Problem

Agent Control supports behavioral governance (toxicity, PII, compliance) but has no concept of financial spend limits. As agents transact autonomously via x402 and other payment protocols, enterprises need governance over what agents spend.

Proposed Solution

Add a financial-governance evaluator type that can:

• Track cumulative agent spend per policy period
• Enforce per-transaction and per-period financial limits
• Interface with wallet SDKs to validate transactions before execution

Reference Implementation

agentpay-mcp (npm: agentpay-mcp, v1.2.0) is an open-source MCP server implementing non-custodial x402 payments with on-chain spend limits. Could serve as a reference evaluator.

Key features mapping to Agent Control policies:

• Per-transaction spend caps
• Rolling period budgets
• Allowlisted recipient addresses
• Transaction queuing when limits exceeded

Happy to contribute if interested.

[lan17]

This is a great idea, and we had similar ones brewing internally as well.

Agree with the direction of implementing this as an evaluator.

Some thoughts on how it should be implemented:

1. This will likely require a new table/database. Evaluator should be decoupled from the data source so different databases or stores could be used for tracking.
2. We probably should not add new tables to core agent control, hence decoupling idea above.
3. Ideally the rules for limits could take into account more context, such as extra context/metadata we pass into evaluate. This way we could have different limits for different channels an agent might be in.
4. This new evaluator should also be executable in Python sdk, which should be easy since we share evaluation engine between server and Python sdk.