Enables Claude to fetch and analyze content from web URLs. Claude can only fetch URLs that appear in the conversation context (user messages or previous tool results). For security reasons, Claude cannot dynamically construct URLs to fetch.
Requires the web-fetch-2025-09-10 beta header.
Learn more in https://docs.claude.com/en/docs/agents-and-tools/tool-use/web-fetch-tool.
Usage
claude_tool_web_fetch(
max_uses = NULL,
allowed_domains = NULL,
blocked_domains = NULL,
citations = FALSE,
max_content_tokens = NULL
)Arguments
- max_uses
Integer. Maximum number of fetches allowed per request.
- allowed_domains
Character vector. Restrict fetches to specific domains. Cannot be used with
blocked_domains.- blocked_domains
Character vector. Exclude specific domains from fetches. Cannot be used with
allowed_domains.- citations
Logical. Whether to include citations in the response. Default is
TRUE.- max_content_tokens
Integer. Maximum number of tokens to fetch from each URL.
See also
Other built-in tools:
claude_tool_web_search(),
google_tool_web_fetch(),
google_tool_web_search(),
openai_tool_web_search()
Examples
if (FALSE) { # \dontrun{
chat <- chat_claude(beta_headers = "web-fetch-2025-09-10")
chat$register_tool(claude_tool_web_fetch())
chat$chat("What are the latest package releases on https://tidyverse.org/blog")
} # }