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 H...
This record as markdown: /tools/io-github-saloprj-dialogbrain/web-fetch.md
What web_fetch does on Dialogbrain
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.
| Parameter | Type | Required | Description |
|---|---|---|---|
url | string | Yes | URL to fetch (http or https). Must be publicly reachable. |
extract | string | — | 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.
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 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 signalsAccepts URL/endpoint input (url)
Attacks that exploit this kind of access
The rule that runs web_fetch safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Dialogbrain, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For web_fetch, this is the rule to start with:
web_fetch is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Dialogbrain, apply this rule, and every web_fetch call is checked against it from then on.
Questions about 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. It is categorised as a Read tool in the Dialogbrain MCP Server, which means it retrieves data without modifying state.
web_fetch accepts 2 parameters: url, extract. Required: url. The full parameter table on this page comes from the server's own tool schema.
Register the Dialogbrain MCP server in PolicyLayer and add a rule for web_fetch: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Dialogbrain. Nothing to install.
web_fetch is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the web_fetch rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for web_fetch. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
web_fetch is provided by the Dialogbrain MCP server (https://api.dialogbrain.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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