Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add zarpay/rails-template --skill mcp-oauth-setupgit clone --depth 1 https://github.com/zarpay/rails-templateWrote 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/skills/zarpay/rails-template/mcp-oauth-setup)<a href="https://agentmods.dev/skills/zarpay/rails-template/mcp-oauth-setup"><img src="https://agentmods.dev/badge/skills/zarpay/rails-template/mcp-oauth-setup/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/skills/zarpay/rails-template/mcp-oauth-setup"><img src="https://agentmods.dev/badge/skills/zarpay/rails-template/mcp-oauth-setup.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 | $0.00131 | $0.02488 |
| Opus 5 | $0.00066 | $0.01244 |
| Sonnet 5 | $0.00026 | $0.00498 |
| Haiku 4.5 | $0.00013 | $0.00249 |
Grade A, and why
mcp-oauth-setup 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 9d 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 — 222 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Server Authentication & OAuth Dynamic Client Registration
Implement flexible authentication for MCP (Model Context Protocol) server connections. For OAuth providers, auto-discover endpoints and dynamically register as a client — the user just provides the MCP server URL and clicks "Connect." For bearer/API key providers, support both admin-shared and per-agent credentials so different agents can authenticate with different accounts.
When to Use
- Building an admin UI for managing MCP server connections
- Integrating with third-party MCP providers (Linear, Sentry, Granola, Render, etc.)
- Implementing the MCP Streamable HTTP transport with authenticated tool sync
- Adding per-agent credential support so each agent can use its own account
- Adding OAuth to an existing MCP connector/server management system
Core Standards
The OAuth implementation relies on three RFCs:
- RFC 8414 - OAuth Authorization Server Metadata Discovery via
.well-known/oauth-authorization-server - RFC 7591 - Dynamic Client Registration at the provider's registration endpoint
- RFC 7636 - PKCE (S256) for authorization code security
Not all MCP servers use OAuth. Some (e.g., Render) use bearer tokens with API keys and handle account/workspace selection at the MCP protocol level. The credential system must be auth-type-agnostic.
Architecture Overview
Credential Mode (Orthogonal to Auth Type)
credential_mode applies to all auth types (bearer, api_key_header, oauth), not
just OAuth. This is a critical design decision — different agents may need their own
credentials for the same MCP server (e.g., different Render accounts, different Linear
workspaces).
credential_mode = "shared" → Admin provides one credential, all agents use it
credential_mode = "per_agent" → Each agent has its own credential
OAuth Flow
Admin clicks "Connect"
|
v
Discover OAuth metadata (RFC 8414)
| GET /.well-known/oauth-authorization-server
v
Register as OAuth client (RFC 7591)
| POST /oauth/register
v
Redirect to provider consent screen
| GET /oauth/authorize?client_id=...&code_challenge=...
v
Provider redirects back with code
| GET /callback?code=...&state=...
v
Exchange code for tokens
| POST /oauth/token
v
Store tokens, sync tools
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago First seen · 222 lines · 131 tokens per session scan A f938472e1ab3
mcp-oauth-setup is a skill published in the GitHub repository zarpay/rails-template (9 stars, last pushed 27d ago), licensed MIT. It adds 131 tokens to every session and 2,488 once invoked, about $0.0007 per session on Opus 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 2026-08-31.
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