What is Rate Limiting?

1 min read Updated

Rate limiting is a security control that restricts the frequency of operations — transactions per minute, API calls per hour, or spending events per day — preventing abuse, automated attacks, and runaway agent behavior.

WHY IT MATTERS

Rate limiting is a blunt but effective defense. Even if an agent is compromised and every individual transaction passes policy checks, rate limiting prevents it from executing thousands of transactions in rapid succession to drain funds.

For AI agents, rate limiting serves multiple purposes: preventing runaway loops (agent stuck in a spending cycle), defending against automated attacks (compromised agent draining via rapid small transactions), and enforcing operational sanity (an agent shouldn't normally make 100 payments per minute).

Effective rate limiting is layered: per-second limits (burst control), per-minute limits (sustained rate), per-hour limits (operational bounds), and per-day limits (budget alignment). Each layer catches different attack patterns.

HOW POLICYLAYER USES THIS

PolicyLayer rate-limits agent transactions to prevent automated attacks and runaway spending. Configurable limits at multiple time windows (per-minute, per-hour, per-day) catch both burst attacks and sustained draining attempts.

FREQUENTLY ASKED QUESTIONS

How do you set appropriate rate limits?
Analyze the agent's normal transaction pattern. If it typically makes 5-10 transactions per hour, set the limit at 20-30. Allow reasonable bursts but catch anomalous volumes. Adjust based on observed behavior.
Can rate limiting prevent all attacks?
No. A sophisticated attacker working within rate limits can still steal funds slowly. Rate limiting is one layer in defense-in-depth — combine with spending caps, allowlists, anomaly detection, and monitoring.
Should rate limits be different per agent?
Yes. A trading agent needs higher rate limits than a monthly payroll agent. Match rate limits to the agent's operational requirements and risk profile.

FURTHER READING

Enforce policies on every tool call

Intercept is the open-source MCP proxy that enforces YAML policies on AI agent tool calls. No code changes needed.

npx -y @policylayer/intercept
github.com/policylayer/intercept →
// GET IN TOUCH

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