// GLOSSARY -- POLICY ENFORCEMENT

What is Agent Rate Limiting?

1 min read Updated

Restricting the number or frequency of an agent's tool calls within a time window — preventing runaway loops, excessive resource consumption, and denial-of-service patterns against MCP servers.

WHY IT MATTERS

An unconstrained agent loop can fire hundreds of tool calls per minute. Rate limiting caps this velocity to prevent agents from overwhelming MCP servers, consuming excessive resources, or entering infinite retry loops.

Rate limiting complements tool-level permissions. An agent might be permitted to call search — but not 1,000 times per minute. Rate limits add the time dimension to access control.

Smart rate limiting adapts to context: normal operation at 60 calls per minute, automatic throttling when error rates spike, full halt when rate exceeds a critical threshold (circuit breaker pattern).

Agent Rate Limiting isn't theory — define it as policy in PolicyLayer and it's enforced on every tool call.

ENFORCE THIS WITH POLICY →

Enforced before the call runs. Nothing to install.

HOW POLICYLAYER USES THIS

PolicyLayer enforces YAML-defined rate limits on MCP tool calls. Rate limits can be set per tool, per agent, or globally — for example, 60 calls per minute for read_file, 10 per minute for write_file, 100 per minute across all tools. When the limit is exceeded, PolicyLayer denies the call and returns a structured error to the client.

Read the policy-writing guide →

FREQUENTLY ASKED QUESTIONS

How are rate limits defined in PolicyLayer?
In YAML policy files. You specify the tool name (or a wildcard for all tools), the maximum number of calls, and the time window. For example: max 60 calls per 60 seconds for read_file.
Can I set different rate limits per tool?
Yes. Each tool can have its own rate limit in the YAML policy. High-frequency read operations can have generous limits whilst dangerous write operations have strict limits.
What happens when the rate limit is hit?
PolicyLayer denies the tool call and returns a structured error response to the client indicating the rate limit was exceeded. The agent can then decide to wait or take alternative action.

FURTHER READING

Take your agents live. Without losing control.

Route your MCP traffic through PolicyLayer. Every tool call is checked against your policy before it runs: allow, deny, or require approval. Per-identity grants. Full audit log. Live in minutes.

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