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 seb1n/awesome-ai-agent-skills --skill mcp-server-buildinggit clone --depth 1 https://github.com/seb1n/awesome-ai-agent-skillsWrote 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/seb1n/awesome-ai-agent-skills/mcp-server-building)<a href="https://agentmods.dev/skills/seb1n/awesome-ai-agent-skills/mcp-server-building"><img src="https://agentmods.dev/badge/skills/seb1n/awesome-ai-agent-skills/mcp-server-building/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/seb1n/awesome-ai-agent-skills/mcp-server-building"><img src="https://agentmods.dev/badge/skills/seb1n/awesome-ai-agent-skills/mcp-server-building.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00081 | $0.01903 |
| Opus 5 | $0.00041 | $0.00951 |
| Sonnet 5 | $0.00016 | $0.00381 |
| Haiku 4.5 | $0.00008 | $0.00190 |
Grade A, and why
mcp-server-building 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 13d 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 — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Server Building
Build the smallest server that exposes the required capability safely. Treat protocol conformance, business authorization, and model behavior as separate concerns; all three need independent controls.
Inputs
Collect or infer, and label assumptions for, these inputs:
- User jobs and the minimum capabilities needed
- Backing APIs, data stores, file systems, or local processes
- Intended MCP clients, exact protocol revision, and current SDK/runtime constraints
- Local
stdioor remote HTTP transport requirements - Tenant, identity, credential, and authorization model
- Read, write, destructive, billable, or externally visible effects
- Expected volume, latency, pagination, and deployment environment
- Existing schemas, tests, observability, and incident procedures
Ask only for missing facts that materially change the architecture. Consult the current MCP specification and SDK documentation before relying on version-sensitive behavior.
Output contract
Deliver:
- A server design stating scope, trust boundaries, transport, identity flow, and explicit non-goals
- A tool catalog with names, descriptions, structural input/output/error schemas, explicit effect and data-class arrays, authorization mode, idempotency, and error behavior
- Implementation or a file-level implementation plan, according to the user's requested scope
- Unit, integration, authorization, and protocol-interoperability tests
- Verification evidence: commands run, relevant results, and anything not verified
- Deployment, rollback, monitoring, and credential-revocation guidance
- Residual risks and decisions that still require an owner
Use assets/server-design-template.md when a design artifact is useful. Use scripts/validate_tool_manifest.py to lint a JSON tool manifest before implementation or review.
Workflow
1. Bound the capability
Translate the user job into a narrow set of resources, prompts, and tools. Prefer one clear operation per tool. Exclude administrative or broad pass-through operations unless the use case requires them.
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.
- 13d ago First seen · 125 lines · 81 tokens per session scan A 5788ba615772
mcp-server-building is a skill published in the GitHub repository seb1n/awesome-ai-agent-skills (179 stars, last pushed 1mo ago), licensed MIT. It adds 81 tokens to every session and 1,903 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 2026-08-30.
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