append_site_custom_code
Append or prepend code to a custom code field WITHOUT reading the existing content first. Use this when you need to ADD new CSS rules, JS code, or script tags — no need to read first. For full rewrites, use update_site_custom_code instead.
This record as markdown: /tools/webcake-storefront/append-site-custom-code.md
What append_site_custom_code does on Webcake Storefront
AI agents use append_site_custom_code to create or update resources in Webcake Storefront, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Webcake Storefront environment.
Why append_site_custom_code is rated Medium
append_site_custom_code creates or modifies site code (CSS/JS/scripts) without deletion capability, fitting the Write category. Severity is high because injecting arbitrary JavaScript or CSS into a live storefront can deface pages, steal customer data, or break functionality. However, it does not delete data (thus not Destructive) or directly move money (thus not Financial).
From the tool's definition Tool appends code to custom code fields, modifying site content with CSS, JS, and script tags. The description explicitly states 'ADD new CSS rules, JS code, or script tags' — this is creating or modifying data.
Attacks that exploit this kind of access
The rule that runs append_site_custom_code safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Webcake Storefront, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For append_site_custom_code, this is the rule to start with:
append_site_custom_code 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 Webcake Storefront, apply this rule, and every append_site_custom_code call is checked against it from then on.
Questions about append_site_custom_code
Append or prepend code to a custom code field WITHOUT reading the existing content first. Use this when you need to ADD new CSS rules, JS code, or script tags — no need to read first. For full rewrites, use update_site_custom_code instead. It is categorised as a Write tool in the Webcake Storefront MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Webcake Storefront MCP server in PolicyLayer and add a rule for append_site_custom_code: 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 Webcake Storefront. Nothing to install.
append_site_custom_code 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 append_site_custom_code 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 append_site_custom_code. 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.
append_site_custom_code is provided by the Webcake Storefront MCP server (webcake-storefront-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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