Spend & Loop Caps (Budget Safety)

Autonomous agents can occasionally get caught in recursive tool-calling loops (e.g. repeatedly searching a website with slightly different keywords or trying invalid SQL queries). Without strict guardrails, this can generate massive surprise cloud bills.

Circuit Breaker Configuration

Agent Substrate includes a hard budget circuit breaker evaluated before every turn and tool dispatch:

from substrate.agents import ReActAgent

agent = ReActAgent(
    model="claude-3-7-sonnet",
    max_steps=25,             # Terminate if loop exceeds 25 steps
    max_cost_usd=5.00,        # Hard dollar ceiling per session
    max_tokens_per_turn=4000  # Token rate limit
)

What Happens When a Limit Is Reached?

If a run reaches its $5.00 ceiling:

1. Execution Halts Instantly: The next model dispatch is blocked before tokens are billed.
2. Partial Result Returned: The agent returns its latest valid state with a BUDGET_CEILING_REACHED status code.
3. Alert Emitted: An incident event is pushed to your OpenTelemetry / Slack webhook alerting your engineering team.