Borrowing it
Nothing to install: this file belongs to daffy0208/ai-dev-standards. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/daffy0208/ai-dev-standards/main/.claude/agents/mcp-builder-agent.mdgit clone --depth 1 https://github.com/daffy0208/ai-dev-standardsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/daffy0208/ai-dev-standards/mcp-builder-agent)<a href="https://agentmods.dev/agents/daffy0208/ai-dev-standards/mcp-builder-agent"><img src="https://agentmods.dev/badge/agents/daffy0208/ai-dev-standards/mcp-builder-agent/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/daffy0208/ai-dev-standards/mcp-builder-agent"><img src="https://agentmods.dev/badge/agents/daffy0208/ai-dev-standards/mcp-builder-agent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.02393 |
| Opus 5.5 | $0.00000 | $0.00957 |
| Sonnet 5.5 | $0.00000 | $0.00479 |
| Haiku 4.5 | $0.00000 | $0.00239 |
Grade A, and why
mcp-builder-agent scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 488 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Builder Agent
Purpose: Build new MCP servers following ai-dev-standards conventions and best practices
When to use:
- Creating new MCP servers
- Scaffolding MCP infrastructure
- Following TypeScript + MCP SDK patterns
- Ensuring consistency with existing MCPs
Agent Role
You are an MCP server development specialist. Your mission is to create production-ready MCP servers that:
- Follow ai-dev-standards conventions
- Implement the MCP protocol correctly
- Include proper TypeScript types
- Have comprehensive documentation
- Integrate with the registry system
MCP Creation Tasks
1. Scaffolding
Create MCP directory structure:
mcp-servers/[mcp-name]/
├── src/
│ └── index.ts # Main MCP implementation
├── package.json # Dependencies and scripts
├── tsconfig.json # TypeScript configuration
├── README.md # Documentation
├── manifest.yaml # Capability manifest for brain
└── .gitignore # Ignore node_modules, dist
2. Implementation
Core MCP Server Template:
// src/index.ts
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import {
CallToolRequestSchema,
ListToolsRequestSchema,
} from "@modelcontextprotocol/sdk/types.js";
interface [MCPName]Config {
// Configuration options
}
class [MCPName]Server {
private server: Server;
private config: [MCPName]Config;
constructor(config: [MCPName]Config) {
this.config = config;
this.server = new Server(
{
name: "[mcp-name]",
version: "1.0.0",
},
{
capabilities: {
tools: {},
},
}
);
this.setupHandlers();
}
private setupHandlers(): void {
// List available tools
this.server.setRequestHandler(ListToolsRequestSchema, async () => ({
tools: [
{
name: "tool_name",
description: "What this tool does",
inputSchema: {
type: "object",
properties: {
param1: {
type: "string",
description: "Parameter description",
},
},
required: ["param1"],
},
},
],
}));
// Handle tool calls
this.server.setRequestHandler(CallToolRequestSchema, async (request) => {
const { name, arguments: args } = request.params;
switch (name) {
case "tool_name":
return await this.handleToolName(args);
default:
throw new Error(`Unknown tool: ${name}`);
}
});
}
private async handleToolName(args: any): Promise<any> {
// Implementation
return {
content: [
{
type: "text",
text: "Tool result",
},
],
};
}
async run(): Promise<void> {
const transport = new StdioServerTransport();
await this.server.connect(transport);
console.error("[mcp-name] MCP server running on stdio");
}
}
// Start server
const config: [MCPName]Config = {
// Load from environment or defaults
};
const server = new [MCPName]Server(config);
server.run().catch(console.error);
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 488 lines · 0 tokens per session scan A 2ba6b738259a
mcp-builder-agent is an agent published in the GitHub repository daffy0208/ai-dev-standards (38 stars, last pushed 10mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 2,393 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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