Security

Encryption at rest

• Webhook URLs, API tokens, and tool secrets are encrypted with AES-256-GCM
• Inbound hook signing secrets are also encrypted at rest
• Plaintext secrets are never shown again after initial creation

MCP key security

• MCP keys are stored as hashes — only a short prefix is kept for identification
• The full key is shown once at generation; it cannot be recovered
• Each key can be limited to selected tools (job packs use this for least privilege)
• You can turn inbox tools on or off per key in Settings
• Revoke compromised keys immediately from workspace Settings
• Keys are sent as Authorization: Bearer to your workspace MCP URL

OAuth 2.1 (MCP clients)

• Herald supports OAuth 2.1 for MCP clients (with PKCE)
• Access tokens are short-lived; refresh tokens are hashed at rest
• Consent lets you pick workspace, tool allowlist, and inbox access
• HTTPS is required for OAuth redirects

IP allowlists

• Optional per-workspace allowlist of IPs / CIDRs
• Enforced on the MCP gateway after authentication
• Denied requests are recorded in the audit log

Outbound request protection

Before every tool call that hits the internet, Herald blocks requests to private networks, localhost, and link-local addresses. This applies to custom tools and alert channel webhooks.

Inbound webhook verification

• Custom Herald URLs support signing via the x-herald-secret header
• Provider sources (Stripe, GitHub, etc.) verify their native signatures when configured
• Disabled or suspended workspaces reject inbound traffic

Audit logs

Every MCP tool invocation records:

• Tool name
• Success or error status
• Duration
• Auth method (API key or OAuth) without exposing secrets
• Client IP
• Redacted request args
• Error message (truncated) on failure

View recent logs on the workspace Overview page.

Rate limiting & plan limits

• Monthly invocation limits enforced per workspace plan
• Inbound hook count limited per plan
• Gateway rate limits protect channels from runaway agents
• Suspended workspaces cannot invoke tools or receive hooks

See plan details on the pricing page or in workspace Settings.

Team access control

Workspace routes enforce role-based access. Owners manage billing and team; admins manage integrations and keys; members can view and test. See Workspaces & team.

Production recommendations

• Rotate MCP API keys if a key may have been exposed
• Use a scoped key (job pack) so each agent only sees the tools it needs
• Prefer OAuth 2.1 for clients that support it instead of long-lived Bearer keys
• Review audit logs after connecting new tools or team members