Preview an OpenAPI document before adding it as an integration. Call this first when the user provides a spec URL/blob so you can inspect servers, auth schemes, operation count, and tags before
AI agents call previewSpec to retrieve information from Executor without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs read-only inspection of an OpenAPI specification document. It gathers information for review purposes before any action is taken, with no side effects, state changes, or execution of external operations. The preview functionality is purely informational, making it a Read operation with low severity and minimal risk if misused by an agent.
From the tool's definition The tool 'previewSpec' is designed to 'Preview an OpenAPI document before adding it as an integration' and allows inspection of 'servers, auth schemes, operation count, and tags'.
Documented attack patterns abuse exactly the kind of access previewSpec gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Executor, and nothing reaches the server without passing your rules. This is the rule we recommend for previewSpec:
{
"version": "1",
"default": "deny",
"tools": {
"previewSpec": {}
}
}previewSpec is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Preview an OpenAPI document before adding it as an integration. Call this first when the user provides a spec URL/blob so you can inspect servers, auth schemes, operation count, and tags before. It is categorised as a Read tool in the Executor MCP Server, which means it retrieves data without modifying state.
Register the Executor MCP server in PolicyLayer and add a rule for previewSpec: 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 Executor. Nothing to install.
previewSpec 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 previewSpec 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 previewSpec. 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.
previewSpec is provided by the Executor MCP server (rhyssullivan/executor). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 29 Executor tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
29 Executor tools catalogued and risk-classified — across an index of 42,500+ MCP servers.