Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add byerlikaya/claude-starter-kit --skill mcp-buildergit clone --depth 1 https://github.com/byerlikaya/claude-starter-kitWrote 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/byerlikaya/claude-starter-kit/mcp-builder)<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/mcp-builder"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/mcp-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/byerlikaya/claude-starter-kit/mcp-builder"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/mcp-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 | $0.00054 | $0.00962 |
| Opus 5.5 | $0.00022 | $0.00385 |
| Sonnet 5.5 | $0.00011 | $0.00192 |
| Haiku 4.5 | $0.00005 | $0.00096 |
Grade A, and why
mcp-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 1mo 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 — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Builder
Trigger phrases: "MCP server", "build an MCP", "model context protocol", "expose tools to Claude", "MCP tool"
An MCP server exposes tools (actions the model can call), resources (data it can read), and prompts (reusable templates) to any MCP client over a standard protocol. The whole job is: design a small set of clear, well-described tools, validate their inputs, return useful errors, and prove it works with a real client. The protocol is easy; the design of the tools is what makes the server good or useless.
Kit adaptation (local, .claude/): Stack-agnostic — TypeScript (
@modelcontextprotocol/sdk) or Python (mcp/ FastMCP) are the maintained SDKs; match the project's language. §4 Prohibitions apply (no AI trace in generated code/strings). Secrets (API keys the server needs) go via env, never hardcoded — the kit's secret gates apply.
Design first (the tools ARE the product)
- Few, purposeful tools — expose tasks, not a 1:1 mirror of every API endpoint. "create_invoice" beats "post_v2_billing_documents".
- The description is the interface — the model routes on it. Say what it does, when to use it, and what it returns, in plain language. A vague description = an unused or misused tool.
- Typed, validated inputs — a JSON-Schema for each tool; required vs optional explicit; enums over free strings where possible. Reject bad input with a clear message, don't guess.
- Useful returns & errors — return structured, model-readable results; on failure return an actionable error ("no invoice with id X") not a stack trace. Never crash the server on bad input.
- Least privilege — a tool does one scoped thing; destructive actions are explicit and, where possible, confirmable. Don't expose raw SQL / shell unless that is genuinely the product.
What ships with it
1 file 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.
- 1mo ago Changed b684c589065c
- 1mo ago Changed · +5 lines f73272710058
- 1mo ago First seen · 52 lines · 54 tokens per session scan A 11964bdf3da0
mcp-builder is a skill published in the GitHub repository byerlikaya/claude-starter-kit (24 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 962 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.
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