DeepSeek Harness (DSH) uses a plugin-based architecture. However, the built-in @deepseek-ai/dsh-mcp-client only supports static request headers and cannot complete the complex OAuth 2.0 authentication required by mcp.vercel.com (including WWW-Authenticate: Bearer). To interact directly with the Vercel platform, a solution that implements the official OAuth 2.0 client flow is needed.

What Is This

dsh-vercel-mcp is a plugin for DeepSeek Harness (DSH) that provides an official Vercel MCP connection. It implements the OAuth 2.0 flow (dynamic client registration + PKCE S256) and exposes Vercel API features as mcp__vercel__* tools in proxy sessions (deployments, projects, domains, environment variables, DNS records, etc.). It also includes a web settings panel for authorization management.

Core Features

  • Official OAuth 2.0 authentication: Supports dynamic client registration and PKCE S256 validation.
  • Web settings panel: Provides a visual entry point for authorization and supports connection testing.
  • Vercel API tools: Operations for deployments, project management, domains, environment variables, DNS records, and more.
  • Automatic token refresh: Automatically refreshes access tokens when a 401 error is encountered.
  • Agent-assisted tools: Provides helper commands for status queries, OAuth flow control (start/end), testing, and clearing credentials.

Installation and Enablement

Install it via a local link:

dsh plugin --profile web add link:/path/to/dsh-vercel-mcp

After installation, you must restart the DSH host to apply the patch and complete plugin composition.

Typical Usage

Authorize via the web settings panel:
1. Open the DeepSeek Harness web interface.
2. Navigate to Settings > Vercel MCP.
3. Click Start Authorization. The browser will open the Vercel consent page, and the callback will complete automatically.
4. Click Test Connection to verify the discovered tools.

Authorize via agent command:
1. In the chat, ask the agent to run vercel_mcp_oauth_start.
2. Copy the returned authorizeUrl and open it in the browser.
3. After completing authorization, paste the code from the callback into vercel_mcp_oauth_finish.

Use Cases and Notes

This plugin solves the problem that the DSH built-in client does not support OAuth, enabling DSH agents to directly operate on Vercel resources.

Notes:
* Tokens are stored in ~/.dsh/dsh-vercel-mcp.json, with file permissions set to 0600.
* All API routes use the local loopback address (127.0.0.1), except the OAuth callback.
* The DSH host must be restarted after installation to apply the patch.
* Available tools are mapped to mcp__vercel__*.

Conclusion

With this plugin, DSH agents can now interact directly with the Vercel API. The source code is available at: GitHub