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 agentmods add skills/modiqo/skillspec/mcp-buildernpx skills add modiqo/skillspec --skill mcp-buildergit clone --depth 1 https://github.com/modiqo/skillspecWrote 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/modiqo/skillspec/mcp-builder)<a href="https://agentmods.dev/skills/modiqo/skillspec/mcp-builder"><img src="https://agentmods.dev/badge/skills/modiqo/skillspec/mcp-builder.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 | $0.00175 | $0.03121 |
| Opus 5 | $0.00088 | $0.01561 |
| Sonnet 5 | $0.00035 | $0.00624 |
| Haiku 4.5 | $0.00017 | $0.00312 |
Grade A, and why
mcp-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Builder
SkillSpec port of the MCP server development guide for planning, implementing, testing, and evaluating high-quality MCP servers in TypeScript or Python.
Entry Gate
- Before any task action, run
skillspec plan ./skill.spec.yml --input='<user task>' --trace-dir "${PWD}/.skillspec/traces", preserve the printedrun_dir, then runskillspec act ./skill.spec.yml --input='<user task>' --run <run_dir> --phase <phase-id>, and read the ordered phase plan plus current-route action checklist. - Until that plan and checklist are read, the only allowed actions are loading this
SKILL.md, loading the colocatedskill.spec.yml, and running SkillSpec navigation or decision commands for this spec. - The selected route and matched rules in the checklist override lower-level skill defaults. If a tool is forbidden, stop and report that the SkillSpec blocks it.
- After each phase action, record structured progress in
<run_dir>/execution.jsonland runskillspec progress show ./skill.spec.yml --run <run_dir>before moving to the next phase. - Forbidden before the decision: implement_without_research_plan, skip_protocol_docs, run_evaluation_without_approval, execute_destructive_evaluation_tasks.
This skill is a thin loader for the colocated skill.spec.yml. The spec is the source of truth for routes, rules, dependencies, imports, resources, recipes, tests, and trace requirements. Do not treat the spec as background prose; treat it as the execution contract for this task.
Runtime Contract
-
Load
./skill.spec.ymlfrom this skill folder before taking task actions. -
When the
skillspecCLI is available and the spec shape is unfamiliar, runskillspec sensemake ./skill.spec.yml --view indexto learn the section roles, counts, query handles, and navigation grammar without dumping the full YAML. -
Then create the ordered phase plan and current-route action checklist:
skillspec plan ./skill.spec.yml --input='<user task>' --trace-dir "${PWD}/.skillspec/traces" skillspec act ./skill.spec.yml --input='<user task>' --run <run_dir> --phase <phase-id>
What ships with it
11 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.
- skill.spec.yml 39 KB
- source/LICENSE.txt 11 KB
- source/reference/evaluation.md 21 KB
- source/reference/mcp_best_practices.md 7.2 KB
- source/reference/node_mcp_server.md 28 KB
- source/reference/python_mcp_server.md 25 KB
- source/scripts/connections.py 4.8 KB runs code
- source/scripts/evaluation.py 12 KB runs code
- source/scripts/example_evaluation.xml 1.2 KB
- source/scripts/requirements.txt 29 B
- source/SKILL_md.old 8.9 KB
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.
- 6d ago First seen · 131 lines · 175 tokens per session scan A 91352c84b22a
mcp-builder is a skill published in the GitHub repository modiqo/skillspec (739 stars, last pushed 27d ago), licensed Apache-2.0. It adds 175 tokens to every session and 3,121 once invoked, about $0.0009 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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