Fetch Open Graph metadata (title, description, image, favicon, domain) for a URL — the same preview card the Viraly composer renders. Useful when an LLM is composing a post that links somewhere and wants to confirm the link card before publishing. Marked as a write tool because it makes a real ou...
AI agents call get_url_preview to retrieve information from Viraly MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Despite the description's incomplete note about being 'marked as a write tool', this is fundamentally a read operation that queries external metadata without modifying any state in Viraly or the target system. It retrieves preview card data for display/confirmation purposes only. HTTP requests to fetch public metadata are Read category operations.
From the tool's definition Tool fetches and retrieves Open Graph metadata for a URL (title, description, image, favicon, domain). The description explicitly states it 'Fetch[es]' data with 'no side effects' implied by its read-only nature.
Attacks that exploit this kind of access
Fetch Open Graph metadata (title, description, image, favicon, domain) for a URL — the same preview card the Viraly composer renders. Useful when an LLM is composing a post that links somewhere and wants to confirm the link card before publishing. Marked as a write tool because it makes a real outbound HTTP request, but it doesn. It is categorised as a Read tool in the Viraly MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Viraly MCP Server MCP server in PolicyLayer and add a rule for get_url_preview: 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 Viraly MCP Server. Nothing to install.
get_url_preview 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 get_url_preview 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 get_url_preview. 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.
get_url_preview is provided by the Viraly MCP Server MCP server (viraly-io/viraly-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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