HTML Answer MCP

HTML Answer is an MCP server for interactive HTML answer review pages. An agent can render task-specific HTML, ask visible review questions, wait for browser feedback, and receive edited HTML, annotations, answers, and handoff instructions.

The model-facing MCP tools are intentionally small:

• render_html_review
• wait_for_feedback

submit_feedback and export_feedback are internal app-only tools used by the browser review UI.

Install

Requires Node.js >=22.13.0.

The package is pure JavaScript/TypeScript and is intended to run on Windows, Linux, and macOS with a supported Node.js runtime. It publishes both the built dist/ output and the TypeScript source under src/.

Add this server to an MCP client that supports stdio servers:

{
  "mcpServers": {
    "html-answer": {
      "command": "npx",
      "args": ["-y", "html-answer", "--stdio"]
    }
  }
}

After changing MCP server configuration, restart the client so it can load the new tools.

Run without editing MCP config:

npx -y html-answer --stdio

Install globally:

npm install -g html-answer
html-answer --stdio

Browser Review URL

By default, the browser review server listens at:

http://127.0.0.1:8767/

Every rendered page returns a browserUrl like:

http://127.0.0.1:8767/pages/<pageId>

If the MCP server runs on a remote machine, expose the review server through SSH forwarding:

ssh -N -L 8767:127.0.0.1:8767 <user@remote-host>

Then open:

http://127.0.0.1:8767/pages/<pageId>

Configuration

Runtime data is stored in:

~/.html-answer

Useful environment variables:

• HTML_ANSWER_MCP_DATA_DIR: override the data directory.
• HTML_ANSWER_REVIEW_ENABLED=0: disable the browser review server.
• HTML_ANSWER_REVIEW_HOST: review server bind host, default 127.0.0.1.
• HTML_ANSWER_REVIEW_PORT: review server port, default 8767.
• HTML_ANSWER_REVIEW_BASE_URL: URL returned to users in browserUrl.
• HTML_ANSWER_MCP_HTTP_HOST: streamable HTTP MCP host, default 127.0.0.1.
• HTML_ANSWER_MCP_HTTP_PORT: streamable HTTP MCP port, default 8765.
• HTML_ANSWER_MCP_HTTP_TOKEN: optional bearer token for HTTP MCP mode.

The older INTERACTIVE_ANSWER_* environment variables are still accepted as compatibility aliases.

Local Development

npm install
npm run typecheck
npm test

Run from source over stdio:

npm run serve

Build and run the packaged entry:

npm run build
npm start

Run the streamable HTTP endpoint:

npm run build
HTML_ANSWER_MCP_HTTP_TOKEN=change-me npm run start:http

Tool Flow

1. Call render_html_review with title, html, and optional questions.
2. Send the returned browserUrl to the user.
3. Call wait_for_feedback({ "pageId": "..." }).
4. Read structuredContent.annotatedHtml, answers, annotations, and userInstructionPrompt.

wait_for_feedback waits up to 30 minutes by default.

Publishing

Before publishing:

npm test
npm pack --dry-run

Publish to npm:

npm publish

Publishing to npm requires either 2FA enabled on the npm account or a granular access token with bypass 2FA enabled.

The package includes the built MCP server and bundled browser app, so npx -y html-answer --stdio can run without a manual build step.