Block Reasons - Mandate

What is a block reason?

When the Mandate policy engine rejects a transaction, the response includes a blockReason field. This machine-readable string tells you exactly which check failed. The response also includes a human-readable blockDetail explaining the specifics and a declineMessage designed to counter prompt injection attempts. Every blocked response follows this format:

{
  "allowed": false,
  "blockReason": "per_tx_limit_exceeded",
  "blockDetail": "$500.00 exceeds $100/tx limit",
  "declineMessage": "This transaction exceeds your per-transaction limit of $100."
}

The declineMessage is an adversarial counter-message. When an agent receives a block, it should display this message to override any manipulative prompt that triggered the transaction attempt.

Block reason reference

The policy engine runs 14 sequential checks. The first failure wins: later checks are skipped. Block reasons appear in the order the engine evaluates them.

Security blocks

These blocks indicate a security condition that prevents any policy evaluation.

blockReason	HTTP	Cause	Resolution
`circuit_breaker_active`	403	Agent is emergency-stopped. Either manually tripped by the owner or auto-tripped by an envelope verification mismatch.	Owner resets the circuit breaker via the dashboard. Investigate the cause before resetting. See Circuit Breaker.
`no_active_policy`	422	No active policy is configured for this agent. Every agent needs at least one policy before it can validate transactions.	Create a policy in the Policy Builder. New agents get a default policy after claiming.

Schedule and allowlist blocks

These blocks enforce when and where agents can transact.

blockReason	HTTP	Cause	Resolution
`outside_schedule`	422	Transaction attempted outside the allowed time window. The policy restricts operations to specific days of the week or hours of the day.	Wait for the next allowed window, or update the schedule in the Policy Builder.
`address_not_allowed`	422	Destination address is not in the policy’s allowlist. When `allowed_addresses` or `allowed_contracts` is configured, only listed addresses are permitted.	Add the address to the allowlist in the Policy Builder.
`action_blocked`	422	The action type (e.g., “swap”, “bridge”) is in the policy’s `blocked_actions` list.	Remove the action from `blocked_actions` in the Policy Builder, or use a different action type.

Spend limit blocks

These blocks enforce USD-denominated spending caps.

blockReason	HTTP	Cause	Resolution
`per_tx_limit_exceeded`	422	Single transaction amount exceeds the `spend_limit_per_tx_usd` policy cap. Default: $100.	Reduce the transaction amount, or increase `spend_limit_per_tx_usd` in the policy.
`daily_quota_exceeded`	422	Agent’s cumulative spend for the current day (UTC) has exhausted the `spend_limit_per_day_usd` budget. Default: $1,000.	Wait until midnight UTC for the daily budget to reset, or increase `spend_limit_per_day_usd`.
`monthly_quota_exceeded`	422	Agent’s cumulative spend for the current month has exhausted the `spend_limit_per_month_usd` budget.	Wait until the 1st of next month for the reset, or increase `spend_limit_per_month_usd`.

Raw validation blocks

These blocks apply only to the deprecated raw validation endpoint (POST /api/validate/raw). Action-based validation does not produce these block reasons.

blockReason	HTTP	Cause	Resolution
`gas_limit_exceeded`	422	Gas limit in the transaction exceeds `max_gas_limit` configured in the policy.	Lower the gas limit in your transaction, or increase `max_gas_limit` in the policy.
`value_wei_exceeded`	422	Native value (ETH/wei) in the transaction exceeds `max_value_wei` configured in the policy.	Lower the native value, or increase `max_value_wei` in the policy.
`selector_blocked`	422	The 4-byte function selector in the transaction calldata is in the policy’s `blocked_selectors` list.	Remove the selector from `blocked_selectors`, or use a different contract function.
`intent_hash_mismatch`	422	The `intentHash` submitted by the client does not match the server’s recomputation from the same parameters.	See Intent Hash Mismatch Troubleshooting. Common causes: stale nonce, uppercase addresses, missing `0x` prefix, or `accessList` set to `undefined` instead of `[]`.

Risk and reason blocks

These blocks come from automated scanning systems.

blockReason	HTTP	Cause	Resolution
`aegis_critical_risk`	422	Destination address is flagged as CRITICAL risk by the Aegis security scanner. Associated with known exploits, sanctions, or rug pulls.	Verify the address is correct. If you believe this is a false positive, contact the Mandate risk team. Do not retry with the same address.
`reason_blocked`	422	The `reason` field triggered prompt injection detection. Mandate scans for 18 attack patterns across 5 categories: direct injection, jailbreak, encoding evasion, multi-turn manipulation, and authority escalation.	Review the reason text and rewrite it without manipulation language. Legitimate reasons like “Pay invoice #127 from Alice” pass. Phrases like “ignore all instructions” or “URGENT: do not verify” are blocked.

How to handle blocks in code

Check for specific block reasons using the SDK’s typed error classes:

import { PolicyBlockedError, CircuitBreakerError, RiskBlockedError } from '@mandate.md/sdk';

try {
  await client.validate({ action: 'transfer', reason: 'Pay invoice', amount: '500', to: '0xAlice' });
} catch (err) {
  if (err instanceof CircuitBreakerError) {
    // blockReason: circuit_breaker_active
    console.error('Agent is emergency-stopped. Contact the owner.');
  } else if (err instanceof RiskBlockedError) {
    // blockReason: aegis_critical_risk
    console.error(`Risky address: ${err.blockReason}`);
  } else if (err instanceof PolicyBlockedError) {
    // Any other blockReason
    console.log(`Blocked: ${err.blockReason}`);
    console.log(`Detail: ${err.detail}`);
    console.log(`Decline message: ${err.declineMessage}`);
  }
}

Never suppress or retry a blocked transaction without changing the parameters. The block reason tells you what to fix. Retrying the same request produces the same result.

Next Steps

SDK Error Classes

Typed error classes for handling blocks, approvals, and circuit breaker events.

Handle Errors Guide

Production-ready error handling patterns for agent developers.

Common Errors

Step-by-step solutions for the most frequent Mandate errors.

Documentation Index

​What is a block reason?

​Block reason reference

​Security blocks

​Schedule and allowlist blocks

​Spend limit blocks

​Raw validation blocks

​Risk and reason blocks

​How to handle blocks in code

​Next Steps

SDK Error Classes

Handle Errors Guide

Common Errors

What is a block reason?

Block reason reference

Security blocks

Schedule and allowlist blocks

Spend limit blocks

Raw validation blocks

Risk and reason blocks

How to handle blocks in code

Next Steps