Identity and Guardrails

Agent objective

Produce a builder with guardrails, behavioral contracts, and safety controls correctly configured so the agent operates within defined bounds and can be stopped when needed.

When to load this skill

• Deploying an agent in a multi-tenant or public-facing context
• Restricting which tools an agent can call or which topics it can address
• Requiring human approval before certain tool calls
• Needing runtime pause/resume/stop controls
• Enforcing token/iteration/output-length budgets at the contract level

Implementation baseline

import { ReactiveAgents } from "@reactive-agents/runtime";

const agent = await ReactiveAgents.create()
  .withName("assistant")
  .withProvider("anthropic")
  .withReasoning({ defaultStrategy: "adaptive" })
  .withTools({ allowedTools: ["web-search", "http-get", "file-read", "checkpoint"] })
  .withGuardrails({
    injection: true,     // detect prompt injection attempts
    pii: true,           // detect and mask PII in inputs/outputs
    toxicity: true,      // detect toxic content
  })
  .withBehavioralContracts({
    deniedTools: ["file-write", "shell-execute"],
    maxToolCalls: 30,
    maxIterations: 20,
    requireDisclosure: true,   // agent must disclose it is an AI
  })
  .withKillSwitch()   // enables pause/resume/stop/terminate controls
  .withAudit()        // records all tool calls and decisions to audit log
  .build();

Key patterns

Guardrails

.withGuardrails()
// Enables all detectors with defaults: injection=true, pii=true, toxicity=true

.withGuardrails({
  injection: true,           // detect "ignore previous instructions" attacks
  pii: false,                // disable PII masking (e.g., agent legitimately processes PII)
  toxicity: true,
  customBlocklist: ["competitor-product", "internal-codename"],  // substring blocklist
})

Guardrail violations abort the turn and return a structured error — the agent never processes the blocked content.

Behavioral contracts

Full field reference for .withBehavioralContracts(contract):

.withBehavioralContracts({
  deniedTools: ["file-delete", "shell-execute"],    // tools the agent may NEVER call
  allowedTools: ["web-search", "file-read"],        // if set, ONLY these tools are allowed
  maxToolCalls: 50,                                  // hard stop after N total tool calls
  maxIterations: 20,                                 // hard stop after N reasoning iterations
  maxOutputLength: 4000,                             // truncate/block output over N chars
  deniedTopics: ["competitor names", "legal advice"], // topics agent must refuse
  requireDisclosure: true,                           // first response must disclose AI identity
})

Contract violations are enforced at runtime — violations halt the current turn with a ContractViolation error.

Kill switch (runtime control)

.withKillSwitch()
// Enables runtime controls on the built agent handle:

const handle = agent.run("Do a long task...");

// Graceful pause (waits for current phase to finish)
await handle.pause();

// Resume from paused state
await handle.resume();

// Graceful stop (finishes current phase, then stops)
await handle.stop("User requested cancellation");

// Immediate termination
await handle.terminate("Emergency shutdown");

Kill switch controls are no-ops if .withKillSwitch() was not called during build.

Audit

.withAudit()      // records all tool calls, guardrail decisions, and contract checks to an audit trail

Audit events flow to the observability stream — pair with .withObservability() to capture them.

GuardrailsOptions reference

Field	Type	Default	Notes
injection	boolean	true	Prompt injection detection
pii	boolean	true	PII detection and masking
toxicity	boolean	true	Toxic content detection
customBlocklist	string[]	[]	Case-insensitive substring blocklist

BehavioralContract reference

Field	Type	Notes
deniedTools	string[]	Tools that may never be called
allowedTools	string[]	If set, only these tools are allowed
maxToolCalls	number	Hard stop after N total tool calls
maxIterations	number	Hard stop after N reasoning iterations
maxOutputLength	number	Max output characters before truncation
deniedTopics	string[]	Topics the agent must refuse
requireDisclosure	boolean	Agent must disclose AI identity

Pitfalls

• .withGuardrails() with no args enables ALL detectors — disable selectively if your use case legitimately handles PII
• deniedTools in a contract and allowedTools in .withTools() are independent — a tool can be in .withTools({ allowedTools }) but still blocked by a contract's deniedTools
• Kill switch controls (pause, resume, stop, terminate) are no-ops without .withKillSwitch() — no error is thrown, calls are silently ignored
• requireDisclosure enforces the agent states it is AI in its first response — this is a prompt-level enforcement, not cryptographic
• Contract violations raise ContractViolation errors — handle these in your error callback or the agent run will throw
• .withAudit() without a log destination writes to the observability stream — add .withObservability() to capture audit events