update_merchant_product
Change SOME fields on a product already in a Merchant Center feed — the everyday operation, because price and availability move daily. This is a PATCH: only the attributes you name are touched and everything else on the product survives, which is the difference from upsert_merchant_product (a who...
This record as markdown: /tools/hermoso/update-merchant-product.md
What update_merchant_product does on Hermoso
AI agents use update_merchant_product to create or update resources in Hermoso, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Hermoso environment.
Why update_merchant_product is rated Medium
An AI agent can call update_merchant_product faster than any human can review: one bad instruction and it creates or modifies resources in Hermoso by the hundred, each call as confident as the last.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs update_merchant_product safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Hermoso, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For update_merchant_product, this is the rule to start with:
update_merchant_product 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 Hermoso, apply this rule, and every update_merchant_product call is checked against it from then on.
Questions about update_merchant_product
Change SOME fields on a product already in a Merchant Center feed — the everyday operation, because price and availability move daily. This is a PATCH: only the attributes you name are touched and everything else on the product survives, which is the difference from upsert_merchant_product (a whole-row write that wipes anything you leave out). It refuses if the product does not exist rather than quietly creating a half-populated one, and it refuses an empty change rather than sending an update mask with nothing behind it. The reply reports every field Google now holds, so you can see what survived. Free. It is categorised as a Write tool in the Hermoso MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Hermoso MCP server in PolicyLayer and add a rule for update_merchant_product: 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 Hermoso. Nothing to install.
update_merchant_product 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 update_merchant_product 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 update_merchant_product. 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.
update_merchant_product is provided by the Hermoso MCP server (https://app.hermoso.ai/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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