Are citations enabled by default for Claude web fetch?

Definition: No. Anthropic documents citations as an optional web fetch setting, disabled by default. An API request must set citations.enabled to true for Claude to add passage-level citation data for fetched documents.

Key facts

• Anthropic's web fetch tool documentation lists citations as an optional tool parameter.
• The same documentation says that web fetch citations are optional and disabled by default, while web search citations are always enabled.
• Anthropic's Messages API reference describes the web fetch citation configuration as optional and says that citations are disabled by default.
• The API reference defines the output document's enabled field as a boolean with a default of false.

How are citations enabled?

The setting belongs in the web fetch tool object sent with the Messages API request. Anthropic's example uses a web_fetch_20250910 tool and sets enabled to true inside the citations object:

{
  "type": "web_fetch_20250910",
  "name": "web_fetch",
  "citations": {
    "enabled": true
  }
}

The web fetch documentation places this object alongside other optional controls such as max_uses, domain filters and max_content_tokens. Omitting the object leaves the documented default in force. The API reference names the request field CitationsConfigParam and makes its enabled property optional.

What does the response contain?

Web fetch first returns a document block containing the fetched content. When the citation option is enabled, Anthropic's web fetch documentation shows a document-level citations object and a response text block with a citation list. The list can identify a char_location, the document index, the document title, character offsets and the cited text.

The documented fetch result also includes the fetched url, the content document block and retrieved_at, a timestamp for when the content was retrieved. For a PDF, the documentation says that content is returned as base64-encoded data. These fields describe the retrieval result; the optional citation setting controls whether Claude's response carries passage references.

Is web fetch different from web search?

Yes. Anthropic's web fetch documentation explicitly contrasts the two server tools: web search citations are always enabled, whereas web fetch citations are optional and disabled by default. A workflow that uses both tools therefore has different documented defaults for the search result and the fetched document.

For a website owner, this is an API integration setting rather than a page markup instruction. The two Anthropic pages document a request parameter and response blocks; website-side behavior and search visibility effects are undocumented there.

How should an integration check its request?

Inspect the web fetch tool object before sending the request. Anthropic's Messages API reference describes the relevant property path as:

tools[].citations.enabled

The request should contain the boolean value true when the integration needs citation data. The API reference describes the property as optional, so a missing property and an explicit false both leave citations disabled according to the documented default.

Related terms

• Claude web search
• How does Claude web fetch differ from web search?
• Can Claude's API web fetch tool read JavaScript-rendered pages?
• Where does Claude report when fetched content was retrieved?

FAQ

Are citations enabled if the citations object is omitted?

No. Anthropic documents the option as disabled by default. The request must include "citations": {"enabled": true} to turn it on.

Does enabling citations change the fetched page content?

The documentation describes full-content retrieval separately from optional citations. Enabling the setting adds citation information to the response structure; the pages describe no filtering function for this option.

Does this setting apply to Claude web search?

No. Anthropic documents web search citations as always enabled and web fetch citations as optional. This entry covers the API web fetch configuration.

Sources

1. Anthropic, "Web fetch tool", undated
2. Anthropic, "Messages API reference", undated

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