Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add techwolf-ai/ai-first-toolkit/plugin install tool-build-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/techwolf-ai/ai-first-toolkit/build-mcp)<a href="https://agentmods.dev/skills/techwolf-ai/ai-first-toolkit/build-mcp"><img src="https://agentmods.dev/badge/skills/techwolf-ai/ai-first-toolkit/build-mcp.svg" alt="Measured on agentmods" 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 | $0.00124 | $0.02731 |
| Opus 5 | $0.00062 | $0.01366 |
| Sonnet 5 | $0.00025 | $0.00546 |
| Haiku 4.5 | $0.00012 | $0.00273 |
Grade A, and why
build-mcp 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 8d 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 — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Build MCP
Build a Model Context Protocol (MCP) server the right way, end to end. The defining move of this skill: establish the user's context with AskUserQuestion before building anything, then tailor every phase to that context. A personal local server and a public hosted server share almost no steps past "build", so branch early and commit to the branch.
How this relates to mcp-builder
The Anthropic example-skills:mcp-builder skill is the gold-standard reference for the implementation itself: FastMCP and TypeScript SDK patterns, tool design, input/output schemas, annotations, error handling, and evaluation. Do not duplicate it. This skill is the scope-and-distribution wrapper around it: it decides what to build, for whom, where it runs, and how it ships. When you reach the build phase, invoke example-skills:mcp-builder for the deep implementation guidance and keep this skill's references thin.
The five phases
- Analyze: understand the service to wrap and pick the right tool boundaries.
- Build: scaffold and implement the server (delegates to mcp-builder).
- Deploy: get it running and registered for the target runtime.
- Scale: harden and operate it (only substantive for hosted servers).
- Distribute: make it reachable by the intended audience.
Run them in order. The AskUserQuestion answers from Phase 0 gate phases 3, 4, and 5.
Phase 0: Establish context (AskUserQuestion, do this first)
Before analyzing or writing anything, branch on the user's context. Ask the audience question first; it is the headline decision and it cascades into everything downstream. Then ask runtime only if it is still ambiguous, and ask language after Analyze (so you can recommend based on the wrapped service).
Question 1 (always, ask first): Audience / scope:
Use AskUserQuestion:
- header: "Audience"
- question: "Who is this MCP server for? This decides how we deploy and distribute it."
- options:
- "Just me": personal local tool on my machine.
- "My team / org": shared internally, installed by colleagues.
- "Public / external": published openly for anyone to install.
What ships with it
6 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.
- 8d ago First seen · 128 lines · 124 tokens per session scan A e37bcb7db982
build-mcp is a skill published in the GitHub repository techwolf-ai/ai-first-toolkit (98 stars, last pushed 1mo ago), licensed MIT. It adds 124 tokens to every session and 2,731 once invoked, about $0.0006 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 2026-08-30.
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