mcp-oauth-remote-gateway

A setup guide for signing in to remote MCP servers from Hermes, an AI-agent gateway that runs outside your computer. It handles the browser-based OAuth login when the gateway cannot receive a callback through your laptop's local address.

In plain words
What is it for?
Use it to connect a remote HTTP MCP server that requires OAuth 2.1 with PKCE and dynamic client registration, such as services that require browser sign-in.
Why use it?
It fixes a login problem where the authorization response goes to your laptop instead of the remote gateway. The resulting tokens are saved where Hermes can reuse them.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/nousresearch/hermes-agent/mcp-oauth-remote-gateway
Any agent
npx skills add NousResearch/hermes-agent --skill mcp-oauth-remote-gateway
Clone the repo
git clone --depth 1 https://github.com/NousResearch/hermes-agent

Made for: Claude Code, Codex.

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,943 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00020 $0.05943
Opus 5 $0.00010 $0.02972
Sonnet 5 $0.00004 $0.01189
Haiku 4.5 $0.00002 $0.00594

Measured yesterday against content hash e21ffc19f8d1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mcp-oauth-remote-gateway scanned grade A with 1 finding 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 yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/diagnose-oauth-mcp.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

login-gated; a cookieless curl returning 401/302 confirms they exist).
Origin

Copies of this mod

4 near-identical copies found in the catalogue:

optional-skills/mcp/mcp-oauth-remote-gateway/SKILL.md · 372 lines

How it starts

The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP OAuth on a Remote Hermes Gateway

Overview

Hermes' built-in MCP OAuth client runs a one-shot HTTP listener on 127.0.0.1:<port> inside the Hermes process and registers that loopback address as the OAuth redirect_uri. That works perfectly for a local CLI on the user's own machine. It breaks completely when Hermes runs as a remote gateway (container, VPS, messaging bot), because the user's browser resolves 127.0.0.1 to the user's own laptop, not the remote container — so the authorization code never reaches Hermes.

This skill does the OAuth dance by hand and writes the resulting tokens into the exact files Hermes' token storage expects, so a subsequent /reload-mcp finds cached tokens and skips the browser flow entirely.

When to Use

Use this skill when all of the following are true:

  1. The user wants to add a remote HTTP MCP server that requires OAuth (not a static Bearer token).
  2. Hermes is running as a remote gateway (container, VPS, Docker, managed service) — NOT a local CLI on the user's laptop.
  3. The server supports OAuth 2.1 with PKCE and RFC 7591 Dynamic Client Registration (most modern MCP servers do — Better Stack, Linear, Cloudflare, Datadog, etc.). If it doesn't support DCR (GitHub is the notable exception), this skill does not apply — use a pre-registered OAuth App or a Personal Access Token instead.

Do NOT use this for:

  • Local CLI Hermes — just set auth: oauth in mcp_servers.<name> and /reload-mcp. The built-in flow opens a browser and captures the callback on localhost. Works perfectly.
  • Servers that accept a static Bearer token (API key) — always prefer headers.Authorization: "Bearer <token>" when the user is willing. Simpler, no refresh dance.
  • GitHub Copilot MCP (api.githubcopilot.com/mcp/) — GitHub does not expose DCR. Use a PAT or a pre-registered OAuth App (see pitfall 12).

Why the Built-in OAuth Flow Fails on a Remote Gateway

Hermes' native MCP OAuth client (tools/mcp_oauth.py):

  1. Picks a free local port P.
  2. Registers a dynamic OAuth client with the AS, sending redirect_uri = http://127.0.0.1:P/callback.
  3. Starts an HTTP server on 127.0.0.1:P inside the Hermes process.
  4. Prints the authorize URL and waits for the code at its local endpoint.

Read the full file on GitHub · 372 lines

Files

What ships with it

2 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.

Changes

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.

  1. yesterday First seen · 372 lines · 20 tokens per session scan A e21ffc19f8d1

Subscribe to this mod's changes

mcp-oauth-remote-gateway is a skill published in the GitHub repository NousResearch/hermes-agent (238,457 stars, last pushed yesterday), licensed MIT. It adds 20 tokens to every session and 5,943 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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