Web Fetch Server Tool

Use phaseo:web_fetch when the model needs to read a known URL, such as a documentation page, article, changelog, or PDF-like text source. The model decides when to fetch, provides the URL, and receives bounded page text back as tool context.

How it works

Add { "type": "phaseo:web_fetch" } to tools.
The model decides whether it needs to fetch a URL.
Phaseo fetches and extracts the content using the configured engine.
The extracted text, title, URL, and truncation metadata are returned to the model.
The model writes the final response and may fetch more URLs if needed.

Quick start

curl https://api.phaseo.app/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5-nano",
    "messages": [
      { "role": "user", "content": "Summarize https://phaseo.app/docs/v1/guides/tool-calling" }
    ],
    "tools": [
      { "type": "phaseo:web_fetch" }
    ]
  }'

Configuration

{
  "type": "phaseo:web_fetch",
  "parameters": {
    "engine": "direct",
    "max_chars": 12000,
    "allowed_domains": ["phaseo.app"],
    "blocked_domains": ["internal.example.com"]
  }
}

Parameter	Type	Default	Description
`engine`	string	surface-dependent	Fetch engine: `auto`, `native`, `direct`, `exa`, `parallel`, or `firecrawl`.
`max_chars`	integer	`12000`	Maximum extracted characters returned to the model.
`max_content_tokens`	integer	none	Token-style alias used when `max_chars` is omitted.
`max_uses`	integer	`10`	Maximum fetch calls across the server-tool loop.
`allowed_domains`	string[]	none	Only allow fetches from these domains.
`blocked_domains`	string[]	none	Reject fetches from these domains. Alias: `excluded_domains`.

Engine selection

Engine	Behavior
`auto`	Uses Anthropic native fetch on `/v1/messages`; otherwise Exa if configured; otherwise direct gateway fetch.
`direct`	Fetches directly from the gateway runtime and extracts bounded text.
`exa`	Uses Exa content extraction when configured.
`parallel`	Uses Parallel Extract when configured.
`firecrawl`	Uses Firecrawl Scrape when configured.
`native`	Converts to Anthropic native `web_fetch_20260209` on `/v1/messages`. Other surfaces should use `direct` or a managed engine.

Only HTTP(S) URLs are supported. Direct gateway fetch accepts text-like content types and reduces HTML to plain text before returning it to the model.

Native Anthropic fetch

{
  "model": "claude-sonnet-4.6",
  "max_tokens": 1024,
  "messages": [
    { "role": "user", "content": "Read the docs page and summarize the limits." }
  ],
  "tools": [
    {
      "type": "phaseo:web_fetch",
      "parameters": {
        "engine": "native",
        "max_content_tokens": 9000,
        "allowed_domains": ["phaseo.app"]
      }
    }
  ],
  "tool_choice": { "type": "tool", "name": "phaseo:web_fetch" }
}

Tool result

Managed fetch returns a JSON tool result with fields such as:

{
  "provider": "fetch",
  "engine": "direct",
  "url": "https://phaseo.app/docs/v1/guides/tool-calling",
  "final_url": "https://phaseo.app/docs/v1/guides/tool-calling",
  "status": 200,
  "content_type": "text/html",
  "title": "Tool Calling",
  "text": "...",
  "truncated": false,
  "returned_chars": 8421
}

Check truncated before assuming the model received the full page.

Usage and pricing

Web fetch calls increment:

{
  "usage": {
    "server_tool_use": {
      "web_fetch_requests": 1
    }
  }
}

Managed fetch pricing can use server_tool_web_fetch_requests. Provider-native fetch usage can use native_web_fetch_requests where a model price card defines that meter.

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Web Fetch Server Tool

How it works

Quick start

Configuration

Engine selection

Native Anthropic fetch

Tool result

Usage and pricing

​How it works

​Quick start

​Configuration

​Engine selection

​Native Anthropic fetch

​Tool result

​Usage and pricing

​Related

How it works

Quick start

Configuration

Engine selection

Native Anthropic fetch

Tool result

Usage and pricing

Related