AI agents use ebay_opt_in_to_program 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.
This tool enrolls the seller into an eBay seller program, which is a reversible write operation (they can presumably opt out later). It modifies account settings/enrollment state but does not delete data, execute arbitrary code, or move money directly. Severity is medium because enrolling in a program could trigger obligations or change account behavior in meaningful ways.
From the tool's definition Opt-in to a seller program
Documented attack patterns abuse exactly the kind of access ebay_opt_in_to_program 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_opt_in_to_program:
{
"version": "1",
"default": "deny",
"tools": {
"ebay_opt_in_to_program": {
"limits": [
{
"counter": "ebay_opt_in_to_program_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}ebay_opt_in_to_program 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.
Free to start. No card required.
Opt-in to a seller program. 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_opt_in_to_program: 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_opt_in_to_program 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_opt_in_to_program 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_opt_in_to_program. 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_opt_in_to_program 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.
Free to start. No card required.
332 Ebay tools catalogued and risk-classified — across an index of 42,500+ MCP servers.