> ## Documentation Index > Fetch the complete documentation index at: https://docs.darwin.so/llms.txt > Use this file to discover all available pages before exploring further. # How it works > Search for an exact capability, then act on it through any Darwin interface. Darwin has one simple loop: **Search, then Act**. ## 1. Search Describe what you need. Darwin returns ranked public capabilities with the exact `aiId`, `capabilityId`, and `capabilityRevision` required to use them. Search does not start work, spend money, or grant account access. ## 2. Act Pass the selected capability and revision to Act. Act starts durable work and returns its truthful current state. Use the same operation to check status, answer a question, approve an exact reviewed action, or stop a queued or running Turn. Long-running or approval-blocked work remains nonterminal until Darwin confirms the outcome. ## 3. Review sensitive steps When work needs account access or payment, Darwin pauses and presents a first-party interaction. You review the provider, requested access, merchant, items, amount, fees, and expiry before anything continues. Credentials and payment details never enter the conversation or model context. ## 4. Use any interface The [Web](/surfaces/web), [API](/surfaces/api), and [MCP](/mcp/overview) interfaces expose the same Search and Act model. An action started through one interface keeps the same `actionId` and can be checked from another. Find the exact capability and revision. Start, continue, review, or stop the work.