Local stdio mcp server to get local cache by url from DENO_DIR

deno_cache_fetch-stdio-mcp.ts

import { createCache } from "jsr:@deno/cache-dir";
import { McpServer } from "npm:@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "npm:@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "npm:zod";

const { load } = createCache();

function isUint8Array(arg: string | Uint8Array): arg is Uint8Array {
  return arg.constructor === Uint8Array;
}
async function getLocalCache(url: string): Promise<string | null> {
  const result = await load(url);
  switch (result?.kind) {
    case "module":
      return isUint8Array(result.content)
        ? new TextDecoder().decode(result.content)
        : result.content;
    case "redirect":
      return getLocalCache(result.specifier);
    default:
      return null;
  }
}
const textContent = (text: string, isError = false) => ({
  content: [{ type: "text" as const, text }], isError,
});

const server = new McpServer({
  name: "deno-cache-reader",
  version: "0.1.0",
});

server.registerTool(
  "read_deno_cache",
  {
    description: "Read a file from the Deno cache by URL",
    inputSchema: {
      url: z.string().describe("The URL of the module to read from cache"),
    },
  },
  async ({ url }) => {
    try {
      const text = await getLocalCache(url);
      if (text !== null) {
        return textContent(text);
      } else {
        return textContent(`URL not found in cache: ${url}`, true);
      };
    } catch (error) {
      return textContent(`Error reading cache: ${error}`, true);
    }
  }
);

const transport = new StdioServerTransport();
await server.connect(transport);