web_fetch
Fetch and read content from a SPECIFIC URL. PREFERRED for reading a known page. Returns the page content as readable text/markdown.
This record as markdown: /tools/cowork-os/web-fetch.md
What web_fetch does on CoWork OS
AI agents call web_fetch to retrieve information from CoWork OS without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why web_fetch is rated Low
This tool retrieves and parses remote content from a specified URL without modifying, executing, or deleting anything. The requirement for a SPECIFIC URL (rather than arbitrary execution) further constrains it to safe data retrieval. While there are minor security considerations around SSRF or accessing sensitive URLs, the tool itself is fundamentally a read operation with minimal blast radius if misused by an agent.
From the tool's definition Tool description explicitly states 'Fetch and read content from a SPECIFIC URL' and 'Returns the page content as readable text/markdown'.
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 CoWork OS, 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 CoWork OS, apply this rule, and every web_fetch call is checked against it from then on.
Questions about web_fetch
Fetch and read content from a SPECIFIC URL. PREFERRED for reading a known page. Returns the page content as readable text/markdown. It is categorised as a Read tool in the CoWork OS MCP Server, which means it retrieves data without modifying state.
Register the CoWork OS 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 CoWork OS. 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 CoWork OS MCP server (CoWork-OS/CoWork-OS). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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