workers-oauth-provider is a library that adds OAuth 2.1 authorization to HTTP APIs and remote MCP servers running on Cloudflare Workers. It is for protecting Worker routes, validating bearer tokens, and supporting authorization discovery for MCP clients. The catalogue entry is an instruction for using this library.
Borrowing it
Nothing to install: this file belongs to cloudflare/workers-oauth-provider. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/cloudflare/workers-oauth-provider/main/AGENTS.mdgit clone --depth 1 https://github.com/cloudflare/workers-oauth-providerWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/cloudflare/workers-oauth-provider/agents-md)<a href="https://agentmods.dev/instructions/cloudflare/workers-oauth-provider/agents-md"><img src="https://agentmods.dev/badge/instructions/cloudflare/workers-oauth-provider/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/cloudflare/workers-oauth-provider/agents-md"><img src="https://agentmods.dev/badge/instructions/cloudflare/workers-oauth-provider/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.03089 | $0.03089 |
| Opus 5.5 | $0.01236 | $0.01236 |
| Sonnet 5.5 | $0.00618 | $0.00618 |
| Haiku 4.5 | $0.00309 | $0.00309 |
Grade A, and why
workers-oauth-provider AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 296 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
Project overview
@cloudflare/workers-oauth-provider is a production-grade OAuth 2.1 provider library for Cloudflare Workers. It implements authorization code flow with PKCE, OAuth discovery, client registration, token exchange, audience validation, and encryption of sensitive data stored in KV.
Primary use case: This library powers authorization for MCP (Model Context Protocol) servers. MCP servers are OAuth Resource Servers, and this library provides both protected-resource middleware and the authorization server functionality needed to secure them.
This library was largely written with Claude AI assistance, with all code thoroughly reviewed by Cloudflare security engineers.
MCP specification compliance
When modifying OAuth functionality, always check the latest published MCP specification (not drafts):
- Specification: https://modelcontextprotocol.io/specification/2026-07-28
- Authorization section: https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization
- Authorization server discovery: https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization/authorization-server-discovery
- Client registration: https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization/client-registration
- Security considerations: https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization/security-considerations
This library must be feature-complete with the latest published MCP spec version. Key MCP auth requirements:
- MCP servers are OAuth Resource Servers with protected resource metadata (RFC 9728)
- MCP clients use Resource Indicators (RFC 8707), and servers validate token audience
- Client registration supports pre-registration and Client ID Metadata Documents (CIMD)
- Dynamic Client Registration (DCR) is deprecated in MCP 2026-07-28 and retained for compatibility
- Authorization responses use issuer identification (RFC 9207)
- Streamable HTTP transport uses OAuth 2.1 for authentication
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago Changed · +42 tokens per session aa0dc3a136d4
- 21d ago Changed · +1 lines · +29 tokens per session 4db5148e1f3c
- 28d ago Changed · -4 tokens per session 6ebc624ef8ed
- 1mo ago Changed · +3 lines · +69 tokens per session 7c11883e42c1
- 1mo ago Changed · +10 lines · +368 tokens per session 6ed8ad19613d
- 1mo ago Changed · +5 lines · +168 tokens per session 5b4d195ba1aa
- 1mo ago First seen · 277 lines · 2,417 tokens per session scan A 242c2bd084c3
workers-oauth-provider AGENTS.md is an instructions file published in the GitHub repository cloudflare/workers-oauth-provider (1,889 stars, last pushed 5d ago), licensed MIT. It adds 3,089 tokens to every session, about $0.0124 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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