AI agents use ebay_update_offer to create or update resources in Ebay — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ebay environment.
Updating offers on eBay modifies pricing, inventory, terms, or other listing properties that affect active sales and customer interactions. While reversible (can be updated again), this is a Write operation rather than Read (retrieves data) or Execute (runs arbitrary code). The high severity reflects the business impact of malicious or erroneous offer modifications affecting multiple listings and potentially revenue.
From the tool's definition Tool name 'ebay_update_offer' and description 'Update an existing offer' indicate modification of existing data. The 'update' verb and context within eBay's Sell APIs (inventory management, order fulfillment) confirm this is a data modification operation.
Documented attack patterns abuse exactly the kind of access ebay_update_offer gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ebay, and nothing reaches the server without passing your rules. This is the rule we recommend for ebay_update_offer:
{
"version": "1",
"default": "deny",
"tools": {
"ebay_update_offer": {
"limits": [
{
"counter": "ebay_update_offer_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}ebay_update_offer 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.
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Update an existing offer. It is categorised as a Write tool in the Ebay MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Ebay MCP server in PolicyLayer and add a rule for ebay_update_offer: 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 Ebay. Nothing to install.
ebay_update_offer 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 ebay_update_offer 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 ebay_update_offer. 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.
ebay_update_offer is provided by the Ebay MCP server (yosefhayim/ebay-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 332 Ebay tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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332 Ebay tools catalogued and risk-classified — across an index of 42,500+ MCP servers.