# web_fetch

Fetches a single URL and returns its content. Use this when you have a specific URL in mind — for example, after web.search returns a link you want to read, or when the user pastes a URL. Modes (extract): - 'auto' (default): picks the right mode based on response content type. - 'markdown': for HTML pages; returns cleaned markdown plus the page <title>. - 'text': for JSON/XML/plaintext APIs; returns the raw decoded body. - 'file': for images, PDFs, audio, video, archives, or any binary — ingests the bytes into the user's file storage and returns a file_id you can pass to messages.send (to send as an attachment), agents.add_file (to add to agent knowledge), or files.read. Use web.fetch (not files.upload) when you need the file_id immediately for the next tool call — files.upload(source_url=…) is async and won't have the file ready in the same turn. Use web.search (not web.fetch) when you don't have a specific URL yet and need to find one.

Agent View of the PolicyLayer registry record for `web_fetch`. HTML page: https://policylayer.com/tools/io-github-saloprj-dialogbrain/web-fetch

## Facts

- Tool: `web_fetch`
- Server: Dialogbrain (`https://api.dialogbrain.com/mcp`) — https://policylayer.com/tools/io-github-saloprj-dialogbrain.md
- Homepage: https://github.com/saloprj/dialogbrain-mcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 2 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `url` | string | yes | URL to fetch (http or https). Must be publicly reachable. |
| `extract` | string | no | How to handle the response: 'auto' (default), 'markdown' (HTML → markdown), 'text' (raw body), or 'file' (ingest as binary, return file_id). |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "web_fetch",
    "arguments": {
      "url": "<url>"
    }
  }
}
```

## Why web_fetch is rated Low

This tool retrieves and reads content from URLs without modifying data or triggering external operations. The 'file' mode stores binary content but does not execute it. The function is purely informational retrieval, fitting the Read category. Severity is low because misuse would only expose data the agent can already access via the internet, with no destructive or financial impact.

From the tool's own definition: "Tool description states it 'Fetches a single URL and returns its content' with modes that retrieve and return data ('picks the right mode based on response content type', 'returns cleaned markdown', 'returns the raw decoded body', 'ingests the bytes into the…"

Risk signals: Accepts URL/endpoint input (url)

## Use case

AI agents call web_fetch to retrieve information from Dialogbrain without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Dialogbrain:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "web_fetch": {}
  }
}
```

## Other tools on Dialogbrain (224)

- `agents_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/agents-delete.md
- `agents_trigger_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/agents-trigger-delete.md
- `ai_filters_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/ai-filters-delete.md
- `ai_tags_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/ai-tags-delete.md
- `calendar_delete_event` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/calendar-delete-event.md
- `collections_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/collections-delete.md
- `files_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/files-delete.md
- `folders_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/folders-delete.md
- `integrations_remove_endpoints` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/integrations-remove-endpoints.md
- `messages_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/messages-delete.md
- `notes_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/notes-delete.md
- `reminder_cancel` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/reminder-cancel.md
- `tasks_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/tasks-delete.md
- `threads_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/threads-delete.md
- `widgets_delete` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/widgets-delete.md
- `youtube_delete_comment` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/youtube-delete-comment.md
- `youtube_delete_video` — Destructive — https://policylayer.com/tools/io-github-saloprj-dialogbrain/youtube-delete-video.md
- `agent_handoff` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/agent-handoff.md
- `agents_simulate_inbound` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/agents-simulate-inbound.md
- `android_launch_app` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/android-launch-app.md
- `android_shell` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/android-shell.md
- `android_ui_dump` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/android-ui-dump.md
- `background_run` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/background-run.md
- `browser_attach_meet` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-attach-meet.md
- `browser_click` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-click.md
- `browser_close` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-close.md
- `browser_drag` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-drag.md
- `browser_evaluate` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-evaluate.md
- `browser_fill` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-fill.md
- `browser_fill_form` — Execute — https://policylayer.com/tools/io-github-saloprj-dialogbrain/browser-fill-form.md
- …and 194 more: https://policylayer.com/tools/io-github-saloprj-dialogbrain.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-saloprj-dialogbrain · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-saloprj-dialogbrain