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Fabro’s web_search tool lets agents search the web during workflow execution. It uses the Brave Search API to return titles, URLs, and descriptions for any query. The tool is registered automatically for all provider profiles (Anthropic, OpenAI, Gemini) — no workflow configuration is needed beyond setting the API key.

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Setup

  1. Get a Brave Search API key from the Brave Search API dashboard
  2. Add it to your .env file: 
export BRAVE_SEARCH_API_KEY=BSA...
  1. Verify the key is working:
fabro doctor --live
The doctor output should show Brave Search as “connected”. If the key is missing, web search is reported as a warning — workflows still run, but web_search calls return an error.

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How it works

Agents call the web_search tool with a query string. Fabro sends the query to the Brave Web Search API (/res/v1/web/search) and returns numbered results with title, URL, and description: 
1. Rust Lang
   https://rust-lang.org
   A systems language

2. Rust Book
   https://doc.rust-lang.org/book
   The Rust book
If BRAVE_SEARCH_API_KEY is not set, the tool returns an error explaining that the key is required. The agent can then fall back to other approaches. See the web_search tool reference for parameters and details.

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Permissions

web_search is classified as a shell category tool, requiring the full permission level for auto-approval. At lower permission levels:
  • Interactive mode — the user is prompted to approve each call
  • Non-interactive mode (--auto-approve) — calls are denied

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Example workflow

A workflow that researches a topic before writing about it:
Research workflow: Start → Research → Summarize → Exit
research.fabro
digraph Research {
    graph [goal="Research and summarize a topic"]
    rankdir=LR

    start [shape=Mdiamond, label="Start"]
    exit  [shape=Msquare, label="Exit"]

    research  [label="Research", prompt="Use web_search to find recent information about $goal. Save your findings to research.md."]
    summarize [label="Summarize", shape=tab, prompt="Read research.md and write a concise summary of the key findings."]

    start -> research -> summarize -> exit
}

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Troubleshooting

“BRAVE_SEARCH_API_KEY environment variable is not set” — Add the key to .env or your shell environment. Run fabro doctor --live to verify. “Brave Search API returned status 401” — The API key is invalid or expired. Generate a new key from the Brave Search API dashboard. “Brave Search API returned status 429” — Rate limit exceeded. The Brave Search free tier has usage limits. Upgrade your plan or reduce the frequency of web_search calls.

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Further reading

Tools

Full web_search tool reference — parameters, output format, and error handling.

Permissions

How tool permissions control web search access.