Vercel AI SDK

Superagent lets you keep the Vercel AI SDK workflow you already use while inserting safety checks for every prompt and tool invocation. The TypeScript SDK is a lightweight client that calls your Superagent Guard endpoint and returns structured allow/block decisions.

Overview

When building AI agents that can execute commands, access files, or interact with external systems, security is paramount. Superagent acts as a security layer that:

Validates user prompts before they reach your AI model
Guards tool executions to prevent harmful operations
Filters tool outputs to ensure safe content handling
Provides detailed security analysis with CWE codes and violation types

Prerequisites

Before starting, ensure you have:

Node.js v20.0 or higher
A Superagent account with API key (sign up here)
An OpenAI API key or other LLM provider credentials
Basic familiarity with Mastra agents

Install dependencies

If you have not already added the Guard SDK to your project:

npm install superagent-ai
# or
pnpm add superagent-ai
# or
yarn add superagent-ai

The rest of this guide assumes you already have the Vercel AI SDK configured (for example ai, @ai-sdk/openai, and zod).

Configure the guard client and provider

import { createGuard } from "superagent-ai";
import { createOpenAI } from "@ai-sdk/openai";
import { generateText } from "ai";

const guard = createGuard({
  apiBaseUrl: "https://app.superagent.sh/api/guard", // optional for self-hosted
  apiKey: process.env.SUPERAGENT_API_KEY!,
});

createGuard returns a callable function you can run before the Vercel AI SDK sends a prompt or executes a tool. The guard response contains a decision object (pass/block), optional violation metadata, and a human readable reasoning string.

Guard user inputs before generating text

Call the guard function when you receive user text. Only forward the prompt to the model if the guard status is pass.

export async function generateGuardedText(userPrompt: string): Promise<GuardedResponse> {
  const { decision, reasoning, rejected } = await guard(userPrompt, {
    onBlock: () => console.warn("Blocked prompt:", reasoning),
    onPass: () => console.log("Prompt cleared guard"),
  });

  if (rejected) {
    return {
      text: null,
      safetyAnalysis: {
        decision,
        reasoning
      }
    };
  }

  const { text } = await generateText({
    model: openai("gpt-4o-mini"),
    prompt: userPrompt,
  });

  return {
    text,
    safetyAnalysis: {
      decision,
      reasoning
    }
  };
}

You can surface back reasoning and decision to your user interface, log it for audit purposes, or trigger a fallback experience. The same guard check can run inside handleSubmit with useChat or any server action that frames messages before calling generateText/streamText.

Guard tool execution

When you expose tools (for example shell access, file I/O, or network requests) wrap the tool body with the guard before performing the action.

import { streamText, tool } from "ai";
import { z } from "zod";
import { createGuard } from "superagent-ai";

const guard = createGuard({ apiKey: process.env.SUPERAGENT_API_KEY })

const runCommand = tool({
  description: "Execute a shell command",
  inputSchema: z.object({
    command: z.string().describe("The shell command to execute"),
  }),
  execute: async ({ command }) => {
    const { decision, reasoning, rejected } = await guard(command, {
      onBlock: () => console.warn("Tool call blocked:", reasoning),
    });

    if (rejected) {
      return {
        result: null,
        safetyAnalysis: {
          decision,
          reasoning
        }
      };
    }

    const result = await runShellCommand(command);

    return {
      result,
      safetyAnalysis: {
        decision,
        reasoning
      }
    }
  },
});

const result = await streamText({
  model: openai("gpt-5"),
  prompt: "Inspect the repository and summarize the README.",
  tools: { runCommand },
});

The guard prevents the AI from executing unsafe commands while still allowing compliant tool calls to continue. You can return a structured object when the guard blocks a call so the model can recover gracefully or inform the user.

Guard tool results

You can also vet the data returned by a tool before handing it back to the model. The example below uses Firecrawl to scrape a page, then runs the combined crawl output through Guard so unsafe content never reaches the agent loop.

import { generateText, tool, stepCountIs } from "ai";
import { openai } from "@ai-sdk/openai";
import { z } from "zod";
import { createGuard } from "superagent-ai";
import FirecrawlApp from "@mendable/firecrawl-js";
import "dotenv/config";

const guard = createGuard({ apiKey: process.env.SUPERAGENT_API_KEY });
const app = new FirecrawlApp({ apiKey: process.env.FIRECRAWL_API_KEY });

export const webSearch = tool({
  description: "Search the web for up-to-date information",
  inputSchema: z.object({
    urlToCrawl: z
      .string()
      .url()
      .min(1)
      .max(100)
      .describe("The URL to crawl (including http:// or https://)"),
  }),
  execute: async ({ urlToCrawl }) => {
    const crawlResponse = await app.crawlUrl(urlToCrawl, {
      limit: 1,
      scrapeOptions: {
        formats: ["markdown", "html"],
      },
    });

    if (!crawlResponse.success) {
      throw new Error(`Failed to crawl: ${crawlResponse.error}`);
    }

    const combined = crawlResponse.data
      .map(({ markdown, html }) => markdown ?? html ?? "")
      .join("\n\n");

    const { decision, reasoning, rejected } = await guard(combined, {
      onBlock: () => console.warn("Blocked crawl result:", reasoning),
    });

    if (rejected) {
      return {
        crawl: null,
        safetyAnalysis: {
          decision,
          reasoning,
        },
      };
    }

    return {
      crawl: crawlResponse.data,
      safetyAnalysis: {
        decision,
        reasoning,
      },
    };
  },
});

const main = async () => {
  const { text } = await generateText({
    model: openai("gpt-4o-mini"),
    prompt: "Get the latest blog post from vercel.com/blog",
    tools: {
      webSearch,
    },
    stopWhen: stepCountIs(5),
  });
  console.log(text);
};

main();

When Guard blocks the crawl result, the tool returns a safetyAnalysis payload instead of the scraped data. The agent can then ask the user for a different URL, try a fallback provider, or skip the unsafe step entirely.