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BeliefState brings investor ideas to your AI. BeliefState is a read-only intelligence API for researching what investors believed, when they believed it, and what evidence supported each view. Query it through MCP or REST.

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Get started

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Configure a coding client with an API key

You can also use an API key with an HTTP MCP client. Create a key, then set BELIEFSTATE_API_KEY in the client’s environment.
Run in your terminal:
Open Codex’s MCP tools and confirm get_brief, get_beliefs, and get_tickers appear.
Using another HTTP MCP client with an API key? Point it at https://beliefstate.ai/mcp and send the key as a Bearer token. See the full MCP guide.

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Other ways to connect

Choose how you want to connect.

Connect an AI

Sign in from a supported AI client to query released research.

Use REST

Make a request from trusted code with a Bearer key.

Check coverage

See released tickers and coverage limits before you query.
Check client availability for ChatGPT and Claude. Public directory listings are not available yet; existing connections may still work.

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Build directly with the API

Check released ticker coverage without an API key:
Continue to the REST quickstart for authenticated requests and response handling.

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Explore the API

API reference

Review released endpoints, parameters, and response fields.

OpenAPI spec

Generate types or a client from the published contract.

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What can BeliefState do?

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Inspect a belief

Read an investor’s thesis, confidence when known, catalysts, risks, invalidations, and cited evidence. Review the belief endpoints.

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Track revisions and outcomes

Compare belief changes over time and inspect outcomes where the underlying record supports them. Observation time and publication time remain distinct. Learn about point-in-time queries.

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Check coverage and provenance

Research-source profiles describe coverage and eligibility. Derived sources do not prove the investor’s exact wording or original publication. Read the provenance guide and coverage guide.

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Resources

Keep citations, warnings, data mode, pagination, explicit unknowns, and methodology versions with downstream results. REST API version: v1. See API versioning, the changelog, or contact support.