AI agents call check_block to retrieve information from Groupme without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation to query the blocking status between users. It retrieves information about whether a block relationship exists, with no side effects, data modifications, or irreversible actions. This is clearly a Read category tool with low severity as it poses minimal risk if misused by an AI agent.
From the tool's definition Tool name 'check_block' and description 'Check if a block exists between two users' indicate a query operation that retrieves the status of a block without modifying or deleting anything.
Attacks that exploit this kind of access
Check if a block exists between two users. It is categorised as a Read tool in the Groupme MCP Server, which means it retrieves data without modifying state.
Register the Groupme MCP server in PolicyLayer and add a rule for check_block: 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 Groupme. Nothing to install.
check_block 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 check_block 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 check_block. 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.
check_block is provided by the Groupme MCP server (kalebjs/groupme-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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