Borrowing it
Nothing to install: this file belongs to chainapsis/keplr-wallet-mcp. 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/chainapsis/keplr-wallet-mcp/develop/.claude/skills/mcp-tool-builder/SKILL.mdgit clone --depth 1 https://github.com/chainapsis/keplr-wallet-mcpWrote 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/skills/chainapsis/keplr-wallet-mcp/mcp-tool-builder)<a href="https://agentmods.dev/skills/chainapsis/keplr-wallet-mcp/mcp-tool-builder"><img src="https://agentmods.dev/badge/skills/chainapsis/keplr-wallet-mcp/mcp-tool-builder/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/skills/chainapsis/keplr-wallet-mcp/mcp-tool-builder"><img src="https://agentmods.dev/badge/skills/chainapsis/keplr-wallet-mcp/mcp-tool-builder.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 | $0.00082 | $0.01885 |
| Opus 5 | $0.00041 | $0.00942 |
| Sonnet 5 | $0.00016 | $0.00377 |
| Haiku 4.5 | $0.00008 | $0.00188 |
Grade A, and why
mcp-tool-builder 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 12d 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 — 268 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Tool Builder
Quick Start
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
const server = new McpServer(
{ name: "my-server", version: "1.0.0" },
{ capabilities: { tools: {}, resources: {}, prompts: {}, logging: {} } }
);
// Tool 등록
server.registerTool("greet", {
description: "Greet a user",
inputSchema: { name: z.string().describe("User name") },
}, async ({ name }) => ({
content: [{ type: "text", text: `Hello, ${name}!` }],
}));
// 연결
await server.connect(new StdioServerTransport());
Tool 구현
기본 패턴
server.registerTool(
"tool-name",
{
title: "Display Name", // 선택
description: "Tool description", // 필수
inputSchema: { // Zod 스키마
param1: z.string().describe("Parameter description"),
param2: z.number().optional().default(10),
},
annotations: { // 선택
readOnlyHint: true, // 읽기 전용 (상태 변경 없음)
destructiveHint: false, // 파괴적 작업 아님
idempotentHint: true, // 멱등성 (반복 호출 안전)
},
},
async (args, extra) => {
// args: 파싱된 인자
// extra: { signal, sessionId, authInfo, _meta, sendNotification }
return {
content: [{ type: "text", text: JSON.stringify(result, null, 2) }],
};
}
);
응답 타입
// 텍스트 (JSON 권장)
{ content: [{ type: "text", text: JSON.stringify(data, null, 2) }] }
// 에러
{ content: [{ type: "text", text: JSON.stringify({ error: msg }) }], isError: true }
// 이미지
{ content: [{ type: "image", data: base64String, mimeType: "image/png" }] }
// 구조화된 출력 (outputSchema 정의 시)
{
content: [{ type: "text", text: "..." }],
structuredContent: { key: "value" }
}
Tool Annotations
| Annotation | 의미 |
|---|---|
readOnlyHint: true |
상태 변경 없음 (조회만) |
destructiveHint: true |
데이터 삭제/변경 (주의 필요) |
idempotentHint: true |
여러 번 호출해도 동일 결과 |
openWorldHint: true |
외부 시스템에 영향 |
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 12d ago First seen · 268 lines · 82 tokens per session scan A 74e3c1922ecc
mcp-tool-builder is a skill published in the GitHub repository chainapsis/keplr-wallet-mcp (5 stars, last pushed 4mo ago), licensed MIT. It adds 82 tokens to every session and 1,885 once invoked, about $0.0004 per session on Opus 5. 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 2026-08-31.
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