Connect to Codex

Ask about any US public company and get the real numbers back — revenue, margins, segments, a decade of history. Your assistant stops hallucinating figures and answers from live, verified data, grounded in what each company actually reported. So you can dig into a business, size it up against peers, and move fast on what you find — with every number traceable to where it came from.

Codex, OpenAI's coding agent, speaks the Model Context Protocol (MCP), so the IDE extension and app can pull live fundamentals from OpenCapital as you work. Prefer the terminal? Use the Codex CLI guide instead.

How to connect

Add the server in Codex

Two interchangeable ways to register OpenCapital — use whichever you prefer.

In the Codex IDE extension (VS Code, Cursor, JetBrains), open the gear menu, choose MCP settings → Add server, select Streamable HTTP, name it opencapital (the lowercase id the config key and codex mcp login command both use), and paste the connector URL below.

https://api.opencapital.sh/mcp

Exact menu labels vary by extension version.

Authenticate with OpenCapital

Click Authenticate in Codex, or run the command below. Codex opens your browser to sign in (Google) and approve read-only access, then stores the token for you.

$ codex mcp login opencapital

Now just ask.

You're all set. Ask Codex about fundamentals, segments, or peer comparisons in any session — it'll call OpenCapital as needed, right alongside your code.

Codex calls OpenCapital automatically — no special prefix needed.

Try asking

Works across every Codex surface

One MCP config across the IDE extension, app, and CLI — add it once. Data is read live everywhere.

Read-only by design

Exposes read-only research data from public SEC filings. Codex cannot place trades or change any account.

Troubleshooting

My AI doesn't see OpenCapital 's tools

Make sure the connector is added, enabled, and signed in. Still nothing? Ask it to “use the OpenCapital MCP server” — in ChatGPT, start the message with

@OpenCapital

The sign-in window didn't open

Authorization opens in your browser — allow pop-ups and retry. In Claude Code run /mcp → Authenticate; in the Codex CLI, run codex mcp login opencapital.

It says “needs login” or stopped working

Tokens can expire — re-authorize from your client's connector settings, or remove and re-add the OpenCapital server.

Connection failed or the server is unreachable

Confirm the URL is exactly https://api.opencapital.sh/mcp, the transport is Streamable HTTP (not stdio), and your client is up to date.

Still stuck?

Email support@opencapital.sh and we'll help you get connected.

Disclosures

Informational only — not investment advice

OpenCapital provides financial data and research, not recommendations. Nothing here is an offer or personalized investment, legal, or tax advice — do your own research.

Data sources and accuracy

Derived automatically from public SEC filings and other sources; it may contain errors or delays and is provided “as is.” Verify against primary sources — see our methodology.

Read-only access

The OpenCapital MCP server is read-only — it cannot place trades, move money, or modify any account.

Third-party AI clients

Your prompts and the data returned are processed by your AI client (Claude, ChatGPT, Codex, Cursor) under its own terms. AI can be wrong — verify before acting.

Authorization

Connecting grants read access via OAuth; revoke it anytime from your client's settings. Use is governed by our Terms and Privacy Policy.