For the complete documentation index, see llms.txt. Markdown versions of all docs pages are available by appending .md to any docs URL.
Multi-layered guardrails
Verified : Code examples on this page have been automatically tested and verified.Chain multiple prompt guards so each request passes every check in order, for defense in depth.
You can configure multiple prompt guards that run in sequence, creating defense-in-depth protection. Guards are evaluated in the order they appear in the configuration.
Shared guardrails under llm.policies.guardrails apply to every model. Model-specific guardrails under llm.models[].guardrails are merged in for the selected model, so the effective policy is the shared baseline plus any model-specific checks.
Example configuration that combines shared and model-specific guardrails:
# yaml-language-server: $schema=https://agentgateway.dev/schema/config
llm:
policies:
guardrails:
request:
# Shared layer 1: Fast regex check for known patterns
- regex:
action: reject
rules:
- builtin: ssn
- builtin: creditCard
- builtin: email
rejection:
body: "Request contains PII and cannot be processed"
response:
- regex:
action: mask
rules:
- builtin: ssn
- builtin: creditCard
models:
- name: "*"
provider: openAI
params:
model: gpt-3.5-turbo
apiKey: "$OPENAI_API_KEY"
guardrails:
request:
# Model layer: OpenAI moderation for harmful content
- openAIModeration:
model: omni-moderation-latest
policies:
backendAuth:
key: "$OPENAI_API_KEY"
rejection:
body: "Content blocked by moderation policy"
# Model layer: Custom webhook for domain-specific checks
- webhook:
target:
host: content-safety-webhook.example.com:8000
response:
- webhook:
target:
host: content-safety-webhook.example.com:8000In this example, the shared policy catches obvious PII across every model, while the selected model adds moderation and webhook checks on top. The response-side regex masking from the shared policy still applies to the model.
