npx skills add ...
npx skills add auth0/agent-skills --skill auth0-custom-domains
npx skills add auth0/agent-skills --skill auth0-custom-domains
Use when setting up, verifying, or troubleshooting a custom Auth0 login domain (e.g. login.example.com). Covers CNAME setup, verification, TLS policy, Multiple Custom Domains, and Management API errors — even if the user just says "use my own domain for Auth0 login".
Drive Auth0 custom-domain work end-to-end: Auth0 Management API, DNS provider, verification polling, and the configuration that stitches everything together. Detects the user's DNS provider (Cloudflare, Route 53, Azure DNS, or other) and automates record creation when the provider supports it.
This skill is capability-based, not step-based. It groups the work a user might want to do into five distinct capabilities (setup, troubleshoot, manage, remove, health check), each with its own flow in a dedicated reference file. The main SKILL.md acts as a lobby: it holds the capabilities table, key concepts, prerequisites, and common mistakes that apply across all flows. When a user invokes the skill, pick the matching capability from the table, load its reference file, and follow that flow.
The capability design matches how users actually come to Auth0 custom domain work: "set one up," "mine is broken," "change something," "remove one," or "is my setup still working?" Each intent maps to a distinct flow with its own safety checks and hand-offs.
Ask questions as plain conversational text. Never use structured UI widgets (e.g., AskUserQuestion) except for a single yes/no confirmation immediately before a destructive or irreversible action (create, PATCH, delete). For everything else:
Example of the right pattern for capability routing:
Example of the right pattern for a single input:
If the user's message is primarily about an HTTP error code from the Management API (e.g., "I got a 403", "why is this returning 409?", a pasted error body, a log entry with a status code), answer from this table first. Do not default to general Auth0 knowledge — it leads to wrong advice on the Free-tier 403 case in particular. Only after the error-code answer, offer to route into the matching capability if the user wants to continue (e.g., "want me to walk through Set up with that fix in place?").
| Status and context | Correct diagnosis and fix |
|---|---|
403 on POST /custom-domains (Free tier) | Not a plan-tier problem. Custom domains are available on all plans including Free (confirmed in Auth0 docs: "To set up a free custom domain, Auth0 tenants must have a valid credit card on file for verification purposes and fraud prevention. The credit card will not be charged."). Fix at Dashboard → Tenant Settings → Billing by adding a card. Do NOT suggest a plan upgrade. |
403 on POST /custom-domains with type: self_managed_certs | This is a plan issue. Self-managed certs are Enterprise-only. Either downgrade to type: auth0_managed_certs (works on all plans) or upgrade to Enterprise. |
409 on POST /custom-domains | Domain already exists on this tenant or another. Run auth0 domains list to check; if on another tenant the user owns, delete it there first. Do not retry a fresh create. |
400 on PATCH /custom-domains/{id} with type in body | type is fixed at create time and rejected by PATCH. Route to delete (capability 4) + recreate (capability 1). Warn about auth downtime during the cutover. |
400 with operation_not_supported on relying_party_identifier | Feature-flag gate on the tenant. Retry without relying_party_identifier and ask Auth0 support to enable the flag. |
| 404 on any custom-domain endpoint | Wrong custom_domain_id, or wrong tenant. Verify with auth0 tenants list + auth0 domains list. |
| 429 | Rate limited. Back off; the skill's verify-poll backoff pattern (5s, 10s, 20s, 30s, 60s) avoids this. |
Full error-code reference with all cases and resolutions: references/api.md#error-codes [blocked].
When this skill is invoked and the user is NOT asking about an error code, ask the user which capability they want using a plain numbered list (see Interaction style above). Route to Check domain health first when the user reports a problem without a specific known cause, or when they're unsure which capability they need; it's the safe, read-only starter that will point them to the right follow-up.
| # | Capability | What it does |
|---|---|---|
| 1 | Set up a custom domain | End-to-end: create the domain in Auth0, detect the DNS provider, write the CNAME record (automated on Cloudflare / Route 53 / Azure; guided on other providers), verify ownership, and report what to update in the user's apps. Handles first-time setup and adding to MCD. See references/capability-setup.md [blocked] |
| 2 | Troubleshoot verification | Domain stuck in pending_verification or verification failing. Diagnostic ladder: compare DNS to expected, check for proxies / CNAME flattening / conflicting records / propagation / private-zone issues, then retry. See references/capability-troubleshoot.md [blocked] |
| 3 | Manage existing domains | Surgical edits on already-configured domains: set or change the default (for MCD), update TLS policy, configure the custom client IP header, set the relying party identifier for passkeys, manage per-domain metadata (up to 10 key-value pairs readable from Actions), list domains and show status. Intent-driven. Certificate type is fixed at create time; PATCH rejects type changes. See references/capability-manage.md [blocked] |
| 4 | Remove a custom domain | Delete a domain safely: warn if it's the default, surface dependent applications, delete in Auth0, clean up the CNAME in DNS. See references/capability-remove.md [blocked] |
| 5 | Check domain health | Read-only: list all custom domains, check DNS records match expected values, surface default-domain config, flag anything needing attention. Safe starter capability. See references/capability-health.md [blocked] |
Pick a capability, then follow the flow in its reference file. The Prerequisites and Key Concepts sections below apply across all capabilities.
| Concept | Description |
|---|---|
| CNAME Record | DNS record pointing your custom domain to Auth0's edge (e.g., {tenant}.edge.tenants.auth0.com). Must stay in DNS permanently for certificate renewal |
| Auth0-Managed Certificate | Auth0 provisions and auto-renews TLS certs every ~3 months. Default and recommended. Type is fixed at create time and cannot be changed via PATCH |
| Self-Managed Certificate | TLS terminates at a reverse proxy (Cloudflare, CloudFront, Azure Front Door, or GCP LB). Enterprise only; verification uses TXT instead of CNAME. Type is fixed at create time and cannot be changed via PATCH; to change, delete and recreate the domain |
| NS Detection | Looking up the root domain's nameservers to identify the DNS provider and route to the correct automation tier |
| Multiple Custom Domains (MCD) | Enterprise feature; up to 20 domains per tenant for multi-brand or multi-region |
| Default Custom Domain | When MCD is configured, the domain used when a Management API call doesn't send the auth0-custom-domain header |
| Relying Party Identifier (RPID) | Per-domain relying_party_identifier that decouples the custom domain hostname from the passkey rpId. Set at create or via PATCH. Lets you serve auth at login.example.com while passkeys bind to example.com for cross-surface reuse |
| TLS Policy | tls_policy on the domain controls minimum TLS version / cipher posture for Auth0-managed certs. Default recommended. Set at create or via PATCH |
| Custom Client IP Header | custom_client_ip_header tells Auth0 which request header carries the real client IP when traffic passes through a reverse proxy. Valid values: true-client-ip, cf-connecting-ip, x-forwarded-for, x-azure-clientip. Set at create or via PATCH |
| Domain Metadata | Up to 10 custom key-value pairs attached to a custom domain (keys and values ≤ 255 chars). Read from Actions via event.custom_domain.domain_metadata for per-domain logic (region, brand, env tagging) |
Full schema and token / iss behavior live in references/advanced.md [blocked].
These apply to any capability that writes to the tenant. Check domain health is read-only and can be run first to verify these.
All capabilities use the Management API. Either:
auth0 ...) authenticated to the target tenant (auth0 tenants use <name>), orCheck the active tenant immediately before the first Auth0 CLI command in a capability, not at skill invocation. Do not check the tenant before the user has chosen a capability. If a capability uses only non-CLI tools (e.g., DNS lookups, Cloudflare MCP, direct Management API calls via curl), skip the tenant check entirely.
When the chosen capability does use the Auth0 CLI, run this before the first CLI command:
Look for the row marked as active (or check the active field in the JSON output). Show the active tenant to the user and ask them to confirm it is the intended target. If it's wrong, stop and have the user run:
Then re-confirm before proceeding. For mutating calls (create, PATCH, delete), require explicit confirmation. For read-only CLI flows, surfacing the tenant name (and naming it in the output report) is enough — still never assume the active tenant is correct based on conversational context alone.
Set up a custom domain writes a CNAME. Remove a custom domain deletes one. Troubleshoot verification may suggest a fix that requires a DNS edit. What the skill needs depends on the provider tier:
claude mcp add --transport http cloudflare https://mcp.cloudflare.com/mcp and authorize in the browser.aws sts get-caller-identity.az account show.Plan requirements for automation: None of the three automated tiers require a paid plan on the DNS provider side. Cloudflare DNS record CRUD via the MCP works on the Free plan (Free zones created after Sept 2024 cap at 200 DNS records per zone; Auth0's CNAME counts as one). Route 53 is pay-per-use (~$0.50/hosted zone/month + query costs, not in AWS free tier). Azure DNS is subscription-based with no tier gating; the signed-in identity needs the DNS Zone Contributor role. Full detail per tier in the per-provider sub-files under references/providers/ [blocked] (router: references/providers.md [blocked]).
Custom domains are available on all plan tiers including Free. Free tenants need a credit card on file for identity verification (card is not charged). Without one, POST /custom-domains returns 403. Fix at Dashboard → Tenant Settings → Billing (or the Teams section for Teams-managed tenants).
Surface this as the likely cause on any 403 rather than suggesting a plan upgrade.
Quick index; each entry links to the canonical treatment in the relevant capability file.
| Mistake | See |
|---|---|
| Assuming a 403 on create means plan upgrade | api.md error codes [blocked] |
| Removing the CNAME after verification (breaks cert renewal) | capability-5 interpreting results [blocked] |
Using a subdomain with passkeys without setting relying_party_identifier | capability-3 RPID section [blocked] |
| Trying to change certificate type via PATCH | capability-3 scope note [blocked] |
| Enabling DNS proxy on the CNAME (Cloudflare orange cloud) | capability-2 proxy check [blocked] |
| Enabling CNAME flattening on the zone | capability-2 flattening check [blocked] |
| Deleting and recreating to "unstick" verification | capability-2 what not to do [blocked] |
Not updating SDK domain / issuerBaseURL after verification | capability-1 report next steps [blocked] |
| Calling Management API via tenant domain under MCD | advanced.md auth0-custom-domain header [blocked] |
references/providers/ (cloudflare.md, route53.md, azure-dns.md, manual.md). Open only the sub-file matching the detected provider.auth0-custom-domain header, self-managed certs, token iss behavior, verification troubleshooting deep-dive