List all cells in a horizontal row
AI agents call matrix_list_horizontals to retrieve information from Matrix Pattern MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves data (cells in a row) without side effects, modification, or code execution. It fits the Read category definition: 'retrieves or queries data; no side effects (search, list, get, fetch).' The explicit use of 'List' in both name and description confirms this is a non-destructive query operation.
From the tool's definition Tool name contains 'list' and description states 'List all cells in a horizontal row' — a pure retrieval operation with no modification or execution.
Attacks that exploit this kind of access
List all cells in a horizontal row. It is categorised as a Read tool in the Matrix Pattern MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Matrix Pattern MCP Server MCP server in PolicyLayer and add a rule for matrix_list_horizontals: 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 Matrix Pattern MCP Server. Nothing to install.
matrix_list_horizontals 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 matrix_list_horizontals 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 matrix_list_horizontals. 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.
matrix_list_horizontals is provided by the Matrix Pattern MCP Server MCP server (rodrigo-jm/matrix-pattern). 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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