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Install Omni in LlamaIndex

LlamaIndex ships first-party MCP support via llama-index-tools-mcp. The BasicMCPClient constructor doesn’t take a headers= kwarg directly, so we pass auth through a custom httpx.AsyncClient.

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Prerequisites

  • Omni API key (free — 250 calls/month). Sign up at secapi.ai. Set OMNI_DATASTREAM_API_KEY.
  • llama-index-tools-mcp ≥ 0.4 with llama-index-core ≥ 0.13 and llama-index-llms-anthropic.

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Install

pip install llama-index-tools-mcp llama-index-core llama-index-llms-anthropic httpx

import asyncio, os
import httpx
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec
from llama_index.core.agent.workflow import FunctionAgent
from llama_index.llms.anthropic import Anthropic

async def main():
    http = httpx.AsyncClient(headers={"x-api-key": os.environ["OMNI_DATASTREAM_API_KEY"]})
    mcp = BasicMCPClient("https://api.secapi.ai/mcp", http_client=http)
    tools = await McpToolSpec(client=mcp).to_tool_list_async()

    agent = FunctionAgent(tools=tools, llm=Anthropic(model="claude-sonnet-4-5"))
    response = await agent.run("Show me Apple's latest 8-K filing.")
    print(response)

asyncio.run(main())

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Verify

Run the snippet. The agent should call the filings.latest tool with ticker: AAPL, form: 8-K and print the filing URL plus a short summary.

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Troubleshooting

  • 401 Unauthorized — the httpx.AsyncClient headers didn’t reach the server. Verify the env var is set in the same shell that runs Python: echo $OMNI_DATASTREAM_API_KEY.
  • 429 Too Many Requests — rate limit hit. See GET https://api.secapi.ai/v1/billing for your plan’s cap.
  • AttributeError: BasicMCPClient has no attribute headers — you’re passing headers= to the constructor; that kwarg doesn’t exist. Always wrap auth in a custom httpx.AsyncClient as shown above.
  • Connection timeout — verify the URL ends in /mcp (note the /mcp suffix, not /sse).

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OAuth alternative

For longer-lived workflows that need rotating credentials, swap BasicMCPClient(...) for BasicMCPClient.with_oauth(...) and follow the OAuth-protected-resource metadata at https://api.secapi.ai/.well-known/oauth-protected-resource.

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