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Install Omni in Custom GPT

Two install paths depending on your ChatGPT plan. Path 1 gives a Custom GPT (or any chat) the full MCP toolset via ChatGPT Apps. Path 2 wraps the REST API as an OpenAPI Action so a Custom GPT on any tier can still call OMNI.

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Prerequisites

  • Omni API key (free — 250 calls/month). Sign up at secapi.ai.
  • For Path 1: ChatGPT Pro, Plus, Business, Enterprise, or Edu with a workspace admin who can enable Developer Mode.
  • For Path 2: any ChatGPT tier with access to the GPT Builder.

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Path 1 — ChatGPT Apps + Developer Mode (native MCP)

  1. Workspace admin: Settings → Apps & Connectors → Advanced → Developer Mode → On.
  2. Settings → Apps & Connectors → Create.
  3. MCP Server URL: https://api.secapi.ai/mcp
  4. Authentication: API Key.
  5. Header name: x-api-key. Header value: your Omni API key.
  6. Save. Enable the connector in any chat; the Omni MCP tools are now available.

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Path 2 — Classic Custom GPT + OpenAPI Action (any tier)

This calls the REST API directly. Tool calls work, but you skip MCP’s auto-discovery — your GPT instructions need to spell out which endpoints to use.
  1. In GPT Builder: Configure → Actions → Create new action.
  2. Schema: paste the URL https://docs.secapi.ai/openapi/omni-datastream.v1.json and import.
  3. Authentication: API Key → Auth Type: Custom → Custom Header Name: x-api-key → paste your Omni key as the value.
  4. Privacy policy: https://secapi.ai/privacy-policy (required by the GPT Store).
  5. Save and test in the playground.

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Verify

In a chat with the connector (or Custom GPT) enabled, ask:
Show me Apple’s latest 8-K filing.
The agent should call filings.latest (Path 1) or GET /v1/filings/latest?ticker=AAPL&form=8-K (Path 2) and return the filing URL plus a short summary.

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Troubleshooting

  • “Action returned 401” — x-api-key not configured or wrong. Re-enter the value in the connector / action auth settings.
  • “Server URL invalid” (Path 1) — must be the literal https://api.secapi.ai/mcp (note /mcp suffix, no trailing slash).
  • “Schema import failed” (Path 2) — verify the schema URL returns JSON with curl https://docs.secapi.ai/openapi/omni-datastream.v1.json | head.
  • 429 rate limit — check GET https://api.secapi.ai/v1/billing for your monthly cap; upgrade at secapi.ai/pricing.

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