upload_post_cover_from_url
Download an external image URL into R2 and attach it as the post's featuredImage. Replaces the manual flow of pasting external URLs (which break when the source goes down). Validates content-type starts with image/ and rejects payloads larger than 20 MB. No AI credits charged — only standard stor...
This record as markdown: /tools/io-favcrm-favcrm/upload-post-cover-from-url.md
What upload_post_cover_from_url does on FavCRM
AI agents use upload_post_cover_from_url to create or update resources in FavCRM, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FavCRM environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
postId | string | Yes | The post ID |
sourceUrl | string | Yes | Public http(s) URL to fetch the image from. Must respond with an image/* content-type. |
Parameters from the server's own tool schema.
Why upload_post_cover_from_url is rated Medium
This tool creates or modifies data (attaches a featured image to a post) without irreversible deletion. While it downloads external content and stores it, the operation is reversible—the image can be replaced or removed. The validation checks (content-type verification, 20 MB limit) provide some guardrails but don't change the fundamental Write category.
From the tool's definition The tool description states it will "Download an external image URL into R2 and attach it as the post's featuredImage," which modifies the post by adding/replacing an image attachment. This is a reversible modification operation.
Attacks that exploit this kind of access
The rule that runs upload_post_cover_from_url safely
PolicyLayer is an MCP gateway: it sits between your AI agents and FavCRM, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For upload_post_cover_from_url, this is the rule to start with:
upload_post_cover_from_url stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect FavCRM, apply this rule, and every upload_post_cover_from_url call is checked against it from then on.
Questions about upload_post_cover_from_url
Download an external image URL into R2 and attach it as the post's featuredImage. Replaces the manual flow of pasting external URLs (which break when the source goes down). Validates content-type starts with image/ and rejects payloads larger than 20 MB. No AI credits charged — only standard storage. It is categorised as a Write tool in the FavCRM MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
upload_post_cover_from_url accepts 2 parameters: postId, sourceUrl. Required: postId, sourceUrl. The full parameter table on this page comes from the server's own tool schema.
Register the FavCRM MCP server in PolicyLayer and add a rule for upload_post_cover_from_url: 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 FavCRM. Nothing to install.
upload_post_cover_from_url is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the upload_post_cover_from_url 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 upload_post_cover_from_url. 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.
upload_post_cover_from_url is provided by the FavCRM MCP server (https://api.favcrm.io/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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