tools

tools

Built-in tool implementations for the LLM agent. Tools communicate with a separate browser-server process for web interaction.

Tools

web_fetch

Fetches a web page and extracts its main content. Returns clean, readable HTML suitable for LLM consumption.

• Smart content-type detection: HTML pages go through browser-server (accessibility tree extraction), plaintext is fetched directly via reqwest
• 300 second timeout
• Requires permission: Before fetching, prompts the user to approve access to the target hostname (e.g., example.com). Once approved for a session or project, subsequent fetches to the same hostname proceed without prompting.

web_search

Performs a web search and returns formatted results with titles, URLs, and snippets. The search engine is configurable via the --search-engine CLI flag (default: Google). Supported engines: Kagi and Google.

• Delegates to browser-server for search extraction
• 300 second timeout
• Kagi engine requires a Kagi session (use tcode browser to log in)
• Google engine works without authentication

current_time

Returns the current date and time.

Browser Client

The browser_client module provides an HTTP client for communicating with browser-server:

use tools::browser_client::{BrowserClient, set_global_client};

// Unix socket mode (used by tcode auto-start)
set_global_client(BrowserClient::unix(socket_path));

// TCP mode (for remote browser-server)
set_global_client(BrowserClient::tcp(url, token));

The global client must be initialized before web_fetch or web_search tools are used. tcode handles this automatically.

Adding New Tools

1. Create a new module under src/
2. Define your tool function with the #[tool] attribute macro
3. Export the {name}_tool() constructor from lib.rs
4. Register it in the server (tcode/src/server.rs)

Adding Permission Checks

Tools that access sensitive resources should request user permission via ToolContext:

#[tool]
fn my_tool(
    #[context] ctx: ToolContext,
    resource: String,
) -> impl Stream<Item = Result<String, String>> {
    async_stream::try_stream! {
        if !ctx.permission.ask_permission(
            &format!("Allow access to {}?", resource),
            "resource_type",
            &resource,
        ).await {
            yield Err("Permission denied".to_string());
            return;
        }
        // ... proceed with tool logic
    }
}

The ScopedPermissionManager handles deduplication — concurrent calls with the same (tool, key, value) share a single prompt. Permissions can be granted for one use, the current session, or the project (persisted to disk).