AI agents call get_avatar to retrieve information from Trello without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves information about the authenticated user (their avatar/profile details) with no side effects, altering data, or external operations triggered. It is purely informational and read-only in nature, making it a Read category tool with low severity since it only accesses user's own profile metadata.
From the tool's definition Tool name 'get_avatar' and description 'Get the authenticated member' indicate a retrieval operation that queries user profile information without modifying data.
Documented attack patterns abuse exactly the kind of access get_avatar gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Trello, and nothing reaches the server without passing your rules. This is the rule we recommend for get_avatar:
{
"version": "1",
"default": "deny",
"tools": {
"get_avatar": {}
}
}get_avatar is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the authenticated member. It is categorised as a Read tool in the Trello MCP Server, which means it retrieves data without modifying state.
Register the Trello MCP server in PolicyLayer and add a rule for get_avatar: 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 Trello. Nothing to install.
get_avatar is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_avatar 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 get_avatar. 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.
get_avatar is provided by the Trello MCP server (v4lheru/trello-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Trello, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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76 Trello tools catalogued and risk-classified — across an index of 43,000+ MCP servers.