Claude + Veto

from claude_agent_sdk import Agent, tool
from veto import Veto

veto = Veto(api_key="veto_live_xxx")

@tool
def transfer_funds(from_account: str, to_account: str, amount: float) -> str:
    """Transfer funds between accounts."""
    # Veto validates before the function body runs
    decision = veto.validate(
        tool="transfer_funds",
        arguments={"from_account": from_account, "to_account": to_account, "amount": amount},
        context={"user_role": "agent", "environment": "production"},
    )

    if decision.action != "allow":
        return f"Transfer blocked: {decision.reason}"

    return process_transfer(from_account, to_account, amount)

@tool
def query_database(query: str, table: str) -> str:
    """Execute a database query."""
    decision = veto.validate(
        tool="query_database",
        arguments={"query": query, "table": table},
    )

    if decision.action != "allow":
        return f"Query blocked: {decision.reason}"

    return execute_query(query, table)

agent = Agent(
    model="claude-sonnet-4-6",
    tools=[transfer_funds, query_database],
    instructions="You are a financial operations assistant.",
)

result = agent.run("Transfer $5000 from ops to marketing")

rules:
  - name: block_destructive_writes
    description: Prevent DELETE/DROP on production tables
    tool: delete_records
    when: context.environment == "production"
    action: deny
    message: "Destructive writes blocked in production"

  - name: approve_large_transfers
    description: Human approval for transfers over $1,000
    tool: transfer_funds
    when: args.amount > 1000
    action: require_approval
    approvers: [finance-team]
    message: "Large transfer requires finance team approval"

  - name: block_external_email
    description: Block emails to non-company domains
    tool: send_email
    when: "!args.to.endsWith('@yourcompany.com')"
    action: deny
    message: "External emails require manual sending"

  - name: read_only_queries
    description: Only allow SELECT queries
    tool: query_database
    when: "!args.query.toUpperCase().startsWith('SELECT')"
    action: deny
    message: "Only read-only queries are permitted"