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Open Index is a tool for building domain-specific, accurate, structured data that agents can actually operate on — and for keeping that data correct as things change. You use Open Index to build a brain: a searchable, continuously-improving context graph of your domain. A brain is domain-agnostic — model a support org (product → "has common issue" → issue), a sales pipeline (customer → order), your infrastructure (service → runbook), or anything else. You define the concepts; Open Index stores them, searches them, and draws the map.

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Quickstart

Install, spin up the bundled example brain, and open the explorer in a few minutes.

Core concepts

doc_type, doc_schema, entity, connector — the four primitives a brain is built from.

Create a brain

Define doc_types, author entities, and load them into the search index.

Connect an agent

Expose the brain over MCP so agents can read context and keep it current.

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What a brain is built from

A brain is built from four primitives:
  • doc_type — a concept you want to track and maintain (e.g. service, customer, issue).
  • doc_schema — the fields stored for a given doc_type.
  • entity — one instance of a doc_type, stored per its schema. Every entity can link to others via related_to (the target) + relationship_edge_meaning (free-text edge semantics).
  • connector — an optional source you extract entities from (e.g. an MCP server).

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A context layer for domain-specialized agents

Open Index is designed to sit behind agents specialized for a domain — legal, marketing, customer support, sales, infrastructure, or a domain of your own. The MCP server gives those agents structured context and a validated way to keep that context current:
  • agent prompt — dynamic domain navigation is published through MCP server instructions so supporting hosts can inject it before the first turn.
  • read — navigation_guidelines() refreshes those instructions; search_brain() and get_entity() retrieve domain context.
  • write — put_entity() (add/update an entity), create_doc_type() (define a concept).
Read and write is the default MCP mode, so a domain agent can both use knowledge and maintain it. Add --read-only when the agent should consume context without mutating it.

Join the community

Ask questions, share the brains you’re modelling, or discuss an idea before you build it.