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┌─────────────┐                         ┌─────────────┐
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│   VS Code   │  ──"list tools"──────▶  │ MCP Server  │
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│             │  ◀─tool definitions───  │             │
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└─────────────┘                         └─────────────┘
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       │
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       ▼
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┌─────────────┐                         ┌─────────────┐
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│   Claude    │  ──"npm_package zod"─▶  │ MCP Server  │
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│             │  ◀─{version, weekly..}  │             │
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└─────────────┘                         └─────────────┘
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       │
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       ▼
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  "zod is at v4.3.6 with 86M weekly downloads"

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{
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  "result": {
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    "content": [{
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      "type": "text",
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      "text": {
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        "name": "zod",
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        "version": "4.3.6",
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        "weeklyDownloads": "86,259,569",
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        "repository": "https://github.com/colinhacks/zod"
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      }
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    }]
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  }
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}

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server.tool(
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  "github_repo",
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  "Get GitHub repo info: stars, forks, issues, last update.",
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  {
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    owner: z.string().describe("Repo owner, e.g. 'facebook'"),
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    repo: z.string().describe("Repo name, e.g. 'react'"),
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  },
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  async ({ owner, repo }) => {
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    const res = await fetch(`https://api.github.com/repos/${owner}/${repo}`, {
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      headers: { "Accept": "application/vnd.github.v3+json" },
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    });
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    if (!res.ok) {
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      return {
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        content: [{ type: "text", text: `Repo "${owner}/${repo}" not found.` }],
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        isError: true,
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      };
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    }
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    const data = await res.json();
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    return {
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      content: [{
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        type: "text",
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        text: JSON.stringify({
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          name: data.full_name,
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          description: data.description,
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          stars: data.stargazers_count.toLocaleString(),
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          forks: data.forks_count.toLocaleString(),
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          openIssues: data.open_issues_count,
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          lastPush: data.pushed_at,
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        }, null, 2),
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      }],
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    };
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  }
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);

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server.tool(
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  "check_site",
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  "Check if a site is up. Returns status and response time.",
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  {
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    url: z.string().url().describe("URL to check"),
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  },
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  async ({ url }) => {
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    const start = Date.now();
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    try {
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      const res = await fetch(url, {
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        method: "HEAD",
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        signal: AbortSignal.timeout(10000),
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      });
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      return {
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        content: [{
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          type: "text",
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          text: JSON.stringify({
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            url,
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            status: res.ok ? "up" : "down",
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            httpStatus: res.status,
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            latencyMs: Date.now() - start,
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          }, null, 2),
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        }],
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      };
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    } catch (err) {
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      return {
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        content: [{
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          type: "text",
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          text: JSON.stringify({
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            url,
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            status: "unreachable",
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            error: (err as Error).message,
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          }, null, 2),
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        }],
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        isError: true,
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      };
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    }
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  }
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);