Return the deterministic MCP selector e2e probe payload.
AI agents call selector_probe to retrieve information from Mcp Docs Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a read-only operation that returns probe payload data for end-to-end testing purposes. It has no capability to modify, delete, execute code, or create financial obligations. The deterministic nature and probe context confirm it is diagnostics/inspection only.
From the tool's definition Tool returns a 'deterministic MCP selector e2e probe payload' — it retrieves or generates test/diagnostic data with no side effects. The name 'selector_probe' and description 'return' indicate data retrieval only.
Attacks that exploit this kind of access
Return the deterministic MCP selector e2e probe payload. It is categorised as a Read tool in the Mcp Docs Server MCP Server, which means it retrieves data without modifying state.
Register the Mcp Docs Server MCP server in PolicyLayer and add a rule for selector_probe: 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 Mcp Docs Server. Nothing to install.
selector_probe 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 selector_probe 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 selector_probe. 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.
selector_probe is provided by the Mcp Docs Server MCP server (@mastra/mcp-docs-server). 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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