agent-cost-guardrails

Budget limits and cost guardrails for AI agent frameworks. Prevents runaway API spend with hard budget enforcement, circuit breakers, and per-agent cost tracking.

Zero infrastructure required -- no gateway, no proxy, no external service. Pure Python middleware that hooks into your framework at the process level.

Features

• Hard budget limits with BudgetExceededError on overspend
• Per-call token limits and tokens-per-minute rate limiting
• Circuit breaker that trips after N consecutive violations
• Alert callbacks at configurable thresholds (50%, 80%, 100%)
• Cost breakdown by model and agent
• Thread-safe for multi-agent parallel runs
• Bundled pricing for 30+ models (OpenAI, Anthropic, Google, Mistral, DeepSeek, Meta)
• Custom pricing overrides for any model

Supported Frameworks

Framework	Integration	Hook Mechanism
CrewAI	CrewAIGuardrails	@before_llm_call / @after_llm_call
AutoGen/AG2	AutoGenGuardrails	safeguard_llm_inputs / safeguard_llm_outputs
LangGraph	LangGraphGuardrails	BaseCallbackHandler

Installation

pip install agent-cost-guardrails

Install with framework-specific extras:

pip install agent-cost-guardrails[crewai]    # CrewAI integration
pip install agent-cost-guardrails[autogen]   # AutoGen/AG2 integration
pip install agent-cost-guardrails[langgraph] # LangGraph/LangChain integration
pip install agent-cost-guardrails[all]       # All frameworks

Quick Start

Context Manager

from agent_cost_guardrails import BudgetGuard

with BudgetGuard(max_usd=5.00) as guard:
    # Before each LLM call
    guard.pre_call_check(estimated_tokens=2000)

    # After each LLM call - record actual usage
    guard.post_call_record("gpt-4o", input_tokens=1500, output_tokens=800)

    print(guard.cost_report())

Decorator

from agent_cost_guardrails import budget_limit

@budget_limit(max_usd=5.00)
def run_my_agents(guard=None):
    guard.pre_call_check()
    guard.post_call_record("gpt-4o", input_tokens=1000, output_tokens=500)
    return guard.cost_report()

result = run_my_agents()

CrewAI

from agent_cost_guardrails.integrations import CrewAIGuardrails

guards = CrewAIGuardrails(max_usd=5.00, max_tokens_per_call=4096)
guards.install()  # Registers hooks globally

crew.kickoff()
print(guards.cost_report())

AutoGen / AG2

AutoGen agents chat back and forth to solve problems. Without limits, a debugging loop across 20+ turns can cost $20+ before the conversation naturally ends. AutoGenGuardrails wraps each agent with budget hooks — every LLM call is checked before it executes, and the conversation stops cleanly when the budget runs out.

from autogen import AssistantAgent, UserProxyAgent
from agent_cost_guardrails.integrations import AutoGenGuardrails

def on_budget_alert(threshold, spent, budget):
    if threshold >= 0.8:
        print(f"WARNING: {threshold*100:.0f}% of ${budget:.2f} budget used")

guards = AutoGenGuardrails(
    max_usd=5.00,
    max_tokens_per_call=10000,
    circuit_breaker_max_violations=3,
    on_alert=on_budget_alert,
    default_model="gpt-4o",
)

assistant = AssistantAgent(
    name="coder",
    llm_config={"model": "gpt-4o"},
    system_message="You are a coding assistant.",
)
user_proxy = UserProxyAgent(
    name="executor",
    human_input_mode="NEVER",
    code_execution_config={"work_dir": "workspace"},
)

guards.wrap_agent(assistant)
guards.wrap_agent(user_proxy)

try:
    user_proxy.initiate_chat(
        assistant,
        message="Debug this failing test: test_user_auth.py::test_session_refresh",
        max_turns=30,
    )
except Exception as e:
    print(f"Conversation stopped: {e}")
finally:
    report = guards.cost_report()
    print(f"Total cost: ${report['total_cost_usd']:.4f}")
    print(f"Turns completed: {report['total_calls']}")

See integrations/autogen_example.py for a runnable before/after demo showing a $5.82 unguarded conversation stopped at $0.82 with a $1.00 budget.

LangGraph / LangChain

from agent_cost_guardrails.integrations import LangGraphGuardrails

guards = LangGraphGuardrails(max_usd=2.00)
result = graph.invoke(
    state,
    config={"callbacks": [guards.callback_handler]}
)
print(guards.cost_report())

Alert Callbacks

def my_alert(threshold, current_cost, max_budget):
    print(f"ALERT: {threshold*100}% budget used (${current_cost:.2f}/${max_budget:.2f})")

guard = BudgetGuard(
    max_usd=10.00,
    alert_thresholds=[0.5, 0.8, 1.0],
    on_alert=my_alert,
)

Custom Pricing

from agent_cost_guardrails import set_custom_pricing

set_custom_pricing({
    "my-fine-tuned-model": {
        "input_per_mtok": 5.0,   # $5.00 per 1M input tokens
        "output_per_mtok": 15.0,  # $15.00 per 1M output tokens
    }
})

Cost Report

report = guard.cost_report()
# {
#     "total_cost_usd": 0.0325,
#     "total_input_tokens": 5000,
#     "total_output_tokens": 2000,
#     "total_calls": 3,
#     "budget_usd": 10.0,
#     "remaining_usd": 9.9675,
#     "cost_by_model": {"gpt-4o": 0.0325},
#     "cost_by_agent": {"researcher": 0.02, "writer": 0.0125},
#     "tokens_by_model": {"gpt-4o": {"input": 5000, "output": 2000}}
# }

License

MIT -- see LICENSE for details.