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 oaustegard/claude-skills --skill creating-mcp-serversgit clone --depth 1 https://github.com/oaustegard/claude-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/oaustegard/claude-skills/creating-mcp-servers)<a href="https://agentmods.dev/skills/oaustegard/claude-skills/creating-mcp-servers"><img src="https://agentmods.dev/badge/skills/oaustegard/claude-skills/creating-mcp-servers/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/oaustegard/claude-skills/creating-mcp-servers"><img src="https://agentmods.dev/badge/skills/oaustegard/claude-skills/creating-mcp-servers.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
SkillSpector: 1 finding, up to low
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- low MCP Rug Pull · line 58 pip install without ==version installs the latest release, which could include malicious changes.Fix: Pin the version: pip install package==1.2.3
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 | $0.00044 | $0.01281 |
| Opus 5 | $0.00022 | $0.00641 |
| Sonnet 5 | $0.00009 | $0.00256 |
| Haiku 4.5 | $0.00004 | $0.00128 |
Grade A, and why
creating-mcp-servers 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 yesterday.
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 — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Creating MCP Servers
Build production-ready MCP servers using FastMCP v2 with optimal context efficiency through progressive disclosure patterns.
Core Capabilities
- Apply the core patterns - Four requirements for consistency
- Implement progressive disclosure - Gateway patterns achieving 85-93% token reduction
- Optimize tool descriptions - 65-70% token reduction through proper patterns
- Bundle servers - Package as MCPB files with validation
- Proven gateway patterns - Three complete implementations (Skills, API, Query)
Architecture Decision
1-3 simple tools?
→ Standard FastMCP with optimized tools
Load: references/MANDATORY_PATTERNS.md
5+ related capabilities?
→ Gateway pattern (progressive disclosure)
Load: references/PROGRESSIVE_DISCLOSURE.md
Load: references/GATEWAY_PATTERNS.md
Optimize existing server?
→ Apply mandatory patterns
Load: references/MANDATORY_PATTERNS.md
Package for distribution?
→ MCPB bundler
Load: references/MCPB_BUNDLING.md
Execute: scripts/create_mcpb.py
Need FastMCP documentation?
→ Search references/LLMS_TXT.md for relevant URLs
→ Use web_fetch on gofastmcp.com URLs
Mandatory Patterns (Summary)
Every implementation should meet these four requirements:
- uv (never pip) -
uv pip install fastmcp - Optimized tool descriptions - Annotations, Annotated, concise docstrings
- Authoritative documentation - Fetch from gofastmcp.com via LLMS_TXT.md index
- Apply all patterns - Every implementation meets verification checklist
Details in references/MANDATORY_PATTERNS.md
Documentation Retrieval Workflow
To fetch FastMCP documentation:
1. Read references/LLMS_TXT.md - complete URL index
2. Search for relevant topic keywords
3. Use web_fetch on matched URLs (append .md for markdown)
4. Apply patterns from fetched documentation
Example: Authentication patterns → Search LLMS_TXT.md for "authentication" → web_fetch https://gofastmcp.com/servers/auth/authentication.md
What ships with it
8 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.
- yesterday Changed · -8 lines bd0a842597d0
- 11d ago First seen · 175 lines · 44 tokens per session scan A 41acc748cac6
creating-mcp-servers is a skill published in the GitHub repository oaustegard/claude-skills (148 stars, last pushed 2d ago), licensed MIT. It adds 44 tokens to every session and 1,281 once invoked, about $0.0002 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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