> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hellofriday.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Testing Agents

> Test any agent in isolation with different inputs, models, and configurations before wiring into workflows.

The Agent Tester lets you run any [built-in agent](/core-concepts/agents) in isolation — test different inputs, models, and configurations before wiring agents into full workflows. Open it from the **Tools** section in the sidebar.

## Built-in agents

Browse all available agents in a searchable catalog. Use **Cmd+K** (**Ctrl+K** on Windows/Linux) to focus search, arrow keys to navigate, and **Enter** to expand an agent's spec sheet. Press **Cmd+Enter** (**Ctrl+Enter**) to open the workbench.

When you select an agent, the workbench opens with:

* **Prompt input** — type your prompt and press **Cmd+Enter** (**Ctrl+Enter**) to execute. Use up/down arrows to cycle through prompt history.
* **Example prompts** — expandable examples from the agent's documentation to help you get started.
* **Credential panel** — shows required and optional credentials with connection status. Connect OAuth providers, enter API keys, or manually override any credential. Required credentials block execution until connected.
* **Environment variables** — key-value editor for any additional configuration the agent needs.
* **Artifact upload** — drag and drop files for agents that work with artifacts (CSVs, audio files, databases).
* **Reference panel** — input/output JSON schemas showing what the agent expects and produces.

After executing, the output streams in real time showing text, tool calls (with expandable input/output), and final results. Stats show tokens used, step count, and duration. Each execution is saved in your run history.

## Custom agents

Build and test ad-hoc agents without editing `workspace.yml`. Configure:

* **Provider** — Anthropic, OpenAI, Google, or Groq
* **Model** — dropdown of available models (defaults to Claude Sonnet)
* **System prompt** — custom instructions for the agent
* **<Tooltip tip="Model Context Protocol">MCP</Tooltip> servers** — multi-select to attach tool servers
* **Environment variables** — additional configuration

Type a prompt, execute, and see streaming results. This is useful for prototyping agent configurations before adding them to your space.

## Tips

Different models yield different results. Sometimes an intelligent model like Opus yields the worst output for your use case — and a faster, cheaper model like Haiku or Sonnet works better. Use the Agent Tester to experiment before committing to a configuration.