ddbx plugin (ChatGPT + Codex)

An Agent Plugins 1.0 package that puts ddbx insider dealings into ChatGPT and Codex. It bundles:

• The ddbx MCP server (https://api.ddbx.uk/mcp): read-only, no auth, thin tier only. The server lives in ddbx-data/worker/mcp.ts; this repo only points at it.
• Three skills that teach the assistant how to use the tools well:
  • company-insiders: insider activity at one company (UK, US, SE, NL, Congress)
  • market-scan: the notable dealings across a market over a period
  • daily-recap: ddbx's published daily summary for the UK or US

.agents/plugins/marketplace.json   repo marketplace, so Codex can add this repo directly
plugins/ddbx/
  plugin.json                      root manifest, with the com.openai interface block
  mcp.json                         the remote MCP server
  skills/<name>/SKILL.md           workflows
  skills/<name>/agents/openai.yaml display name + MCP dependency per skill
  assets/icon.png, logo.png        from ddbx-site/public/ios-app-icon-uk.png
SUBMISSION.md                      listing copy and test cases for the submission portal

Connect

The hosted server is public, read-only and needs no API key: https://api.ddbx.uk/mcp.

• Claude: Customize → Connectors → Add custom connector → paste the URL.
• Cursor / VS Code: add an HTTP MCP server named ddbx with that URL.
• Claude Code: claude mcp add --transport http ddbx https://api.ddbx.uk/mcp
• Gemini CLI: gemini extensions install https://github.com/jonwillington/ddbx-plugin
• Codex: codex plugin marketplace add jonwillington/ddbx-plugin
• Smithery: jonathanwillington/ddbx

The repository also carries manifests for the official MCP Registry, Cursor Marketplace, Gemini CLI and OpenAI Agent Plugins.

Contract with ddbx-data

The skills name the MCP tools (search_dealings, get_dealing, get_company, get_daily_summary, search, fetch) and their arguments. Renaming a tool or an argument in worker/mcp.ts breaks this plugin as well as any cached connector: change it additively, then update the skills here.

The skills also restate the thin-tier posture: the analysis prose is not served, so the assistant links to each filing's url and never invents a reason for a rating. If the MCP ever serves analysis behind auth, update the Rules sections.

Test in Codex

codex plugin marketplace add ./          # from this repo root
codex plugin marketplace list

Then enable it in ~/.codex/config.toml:

[plugins."ddbx@ddbx"]
enabled = true

Try: "What did UK directors buy today?", "Any insider buying at Dunelm?", "What has Congress traded in NVDA?".

Once this repo is on GitHub: codex plugin marketplace add jonwillington/ddbx-plugin.

Test in ChatGPT

1. Settings → Security and login → turn on Developer mode.

2. ChatGPT Plugins → + → server URL https://api.ddbx.uk/mcp, authentication None.

3. Copy the plugin_asdk_app_… id from the browser URL.

4. To bundle the skills with it, add plugins/ddbx/.app.json:

   config.json

   Copy

   { "apps": { "ddbx": { "plugin_asdk_app_<id>": {} } } }
   

   and "apps": "./.app.json" inside extensions.com.openai in plugin.json.

5. Test in a Work chat with @ddbx.

Publish

• Your workspace: ChatGPT Plugins → Personal → the plugin's ⋯ menu → Publish. This does not list it publicly.
• Public directory: the submission portal. Needs a verified developer identity, and the domain challenge served at https://api.ddbx.uk/.well-known/openai-apps-challenge (a ddbx-data change). Listing copy and the required test cases are in SUBMISSION.md.