AI agents call pinchtab_list_instances to retrieve information from Pinchtab without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries browser state (open tabs) and returns metadata without creating, modifying, deleting, or executing any operations. It is a straightforward read operation with minimal security risk — an AI agent misusing it would only retrieve information about which tabs are open, which poses no blast radius for data destruction, financial impact, or system compromise.
From the tool's definition Tool description states it 'List[s] all open browser tabs' and 'Returns tab IDs, URLs, and titles' — purely informational retrieval with no state modification or side effects.
Attacks that exploit this kind of access
List all open browser tabs. Returns tab IDs, URLs, and titles. It is categorised as a Read tool in the Pinchtab MCP Server, which means it retrieves data without modifying state.
Register the Pinchtab MCP server in PolicyLayer and add a rule for pinchtab_list_instances: 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 Pinchtab. Nothing to install.
pinchtab_list_instances 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 pinchtab_list_instances 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 pinchtab_list_instances. 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.
pinchtab_list_instances is provided by the Pinchtab MCP server (maderwin/pinchtab-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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