What is the best authentication platform for AI agents and MCP servers in 2026?

As of November 1, 2026: WorkOS AuthKit for most B2B SaaS teams (OAuth 2.1 authorization server for MCP, first one million monthly active users free, enterprise SSO at $125 per connection); Auth0 for AI Agents when agents must call third-party APIs on a user's behalf (Token Vault and CIBA human approval, an add-on that costs 50% of the Auth0 base price); Stytch Connected Apps for the most generous combined free tier (10,000 monthly active users and AI agents free); and Descope when you want agents managed as first-class identities with low-code flows (free to 7,500 MAUs, Pro from $249 a month).

How do MCP servers authenticate users?

The MCP specification (version 2026-07-28) bases authorization on OAuth 2.1. The MCP server is an OAuth resource server and must publish Protected Resource Metadata (RFC 9728) pointing to its authorization server, which issues access tokens after the user logs in and consents. Clients should register through OAuth Client ID Metadata Documents; Dynamic Client Registration is now deprecated but kept for backwards compatibility. Platforms such as WorkOS AuthKit, Auth0, Stytch and Descope provide that authorization server so you do not build the OAuth endpoints yourself.

What does Auth0 for AI Agents cost?

Auth0 for AI Agents is an add-on that adds 50% to the Auth0 base price, rounded up to the dollar, and includes unlimited Token Vault and all forms of CIBA. On B2C plans it is $18 a month on Essentials and $120 on Professional at 500 MAUs, rising to $350 and $800 at 10,000 MAUs. Auth0's Free plan (up to 25,000 MAUs) also lists secure agentic AI workflows.

Is a secrets manager enough to secure AI agent access?

No. A secrets manager stores your own keys. Agent auth solves a different problem: letting a user grant an agent scoped, revocable access to their account in your app or a third-party app, through OAuth consent, without handing over a password or a long-lived key. Most production agents need both.

Quick Answer

Best Auth Platforms for AI Agents and MCP Servers (2026)

Published: November 1, 2026

The short answer

Pick the platform that already fits how your users log in, then check its agent features. As of November 1, 2026:

WorkOS AuthKit — best for B2B SaaS adding an MCP server or agent access; first 1M MAUs free.
Auth0 for AI Agents — best when agents call Google, Slack, GitHub and other APIs on a user’s behalf (Token Vault) or need human approval for risky actions (CIBA).
Stytch Connected Apps — best free tier: 10,000 monthly active users and AI agents free.
Descope — best for treating agents as first-class identities with visual, low-code flows.

The comparison

	WorkOS AuthKit	Auth0 for AI Agents	Stytch Connected Apps	Descope
MCP OAuth 2.1 server	✅	✅	✅	✅
Free tier	First 1M MAUs	Up to 25,000 MAUs	10,000 MAUs + agents, 5 SSO/SCIM connections, 1,000 M2M tokens	7,500 MAUs, 3 SSO, 10,000 M2M exchanges, 2,000 active consents
Paid entry	Usage-based; $2,500 per extra 1M MAUs	Essentials $35 (B2C) / $150 (B2B) + 50% for AI Agents add-on	Pay per use above free tier	Pro from $249/mo (annual)
Enterprise SSO	$125 per connection (volume discounts)	Add-on / Enterprise	5 free, then pay per connection	3 free, 5 on Pro, 10 on Growth
Calling third-party APIs for users	Pipes	Token Vault	Via connected apps	Third-party connectors, consents
Human approval of agent actions	—	CIBA (all forms in add-on)	—	Step-up auth
Best for	B2B SaaS, enterprise SSO	Agents acting across SaaS for users	Startups, free usage	Low-code teams, agent identity

Prices are list USD read from vendor pricing pages on November 1, 2026.

1. WorkOS AuthKit — best for B2B SaaS

WorkOS AuthKit supports OAuth 2.1 as a compatible authorization server for MCP apps, with PKCE, scopes and tool permissions, while your MCP server stays the protected resource. Pricing is the simplest here: the first one million monthly active users are free, then $2,500 per additional million; enterprise SSO and directory sync cost $125 per connection for the first 15, falling to $65 above 50. If you sell to enterprises and are adding an MCP server so customers’ agents can use your product, it is the shortest path.

2. Auth0 for AI Agents — best for delegated API access

Auth0’s agent product addresses two hard problems. Token Vault stores and refreshes users’ OAuth tokens for third-party services so an agent can call, say, Google Calendar or GitHub on the user’s behalf without the model holding the token. CIBA (Client-Initiated Backchannel Authentication) sends an approval request to the user’s device before an agent performs a sensitive action. On the pricing page, the AI Agents add-on adds 50% to the base price: on B2C Essentials it is $18 a month at 500 MAUs and $350 at 10,000; on Professional, $120 and $800. The Free plan (up to 25,000 MAUs) includes basic agentic workflows. Choose it when agents act across many SaaS tools for end users.

3. Stytch Connected Apps — best free tier

Stytch’s Connected Apps turn your app into an OAuth provider that MCP clients and agents can connect to, with role-based access control. Its free tier counts users and agents together — 10,000 monthly active users and AI agents, five SSO or SCIM connections, 1,000 M2M tokens and 10,000 device fingerprints — with no hard caps or pricing cliffs above that. It is a strong default for startups that expect agent traffic to grow before revenue does.

4. Descope — best for agent identity and low-code flows

Descope models agents as first-class identities with centralized policy, and builds login, consent and step-up flows in a visual editor. Free Forever covers 7,500 MAUs, 10,000 M2M exchanges, 2,000 monthly active consents and 2,000 monthly active tokens; Pro starts at $249/month and Growth at $799/month (25,000 MAUs, SCIM, fine-grained authorization, HIPAA BAA), both billed annually. Choose it if product or security teams, not only engineers, will maintain the auth flows.

What the MCP spec now requires

The current MCP specification (2026-07-28) makes your MCP server an OAuth 2.1 resource server that must publish OAuth 2.0 Protected Resource Metadata (RFC 9728) so clients can discover the authorization server. Clients should identify themselves with OAuth Client ID Metadata Documents; Dynamic Client Registration is deprecated and kept only for backwards compatibility. Before you choose a vendor, confirm it supports Client ID Metadata Documents, resource indicators (RFC 8707) and scope challenges in WWW-Authenticate, not just DCR.

How to choose

Already on one of these for human login: stay; all four support MCP OAuth 2.1.
Enterprise B2B with many SSO customers: WorkOS.
Agent books meetings, files tickets, pushes code for users: Auth0 Token Vault + CIBA.
Pre-revenue with growing agent traffic: Stytch.
Low-code, compliance-heavy flows: Descope.

Auth decides who may act; you still need to protect your own keys — see best secrets managers for AI agents and best tools for brokering secrets to AI agents at runtime.

Last verified: November 1, 2026.