// 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).

HOW POLICYLAYER USES THIS

Intercept 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, Intercept denies the call and returns a structured error to the client.

FREQUENTLY ASKED QUESTIONS

How are rate limits defined in Intercept?
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?
Intercept 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

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 →
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