> This page is for version v4.0.
> For other versions, use one of these documentation indexes:
> - v5.0 (default): https://humanloop.com/docs/v5/llms.txt
> - v4.0: https://humanloop.com/docs/v4/llms.txt

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://humanloop.com/docs/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://humanloop.com/docs/_mcp/server.

> Logs contain the inputs and outputs of each time a Prompt, Tool or Evaluator is called.

All [Prompts](./prompts), [Tools](./tools) and [Evaluators](./evaluators) produce Logs. A Log contains the `inputs` and the `output`s and tracks which version of Prompt/Tool/Evaluator was used.

For the example of a Prompt above, the Log would have one `input` called ‘topic’ and the `output` will be the completion.

![A Log which contains an input query](/docs/_fern-img/37bbf419f63780f07dba7bfbd037ab80f4506e17cdf0a24fb13f043de09ee8db.webp)