bubbuild/bub is a small Python runtime for building AI agents that work in shared environments such as conversations with people. It provides a hook-based turn pipeline and runs agents across command-line, Telegram, and other channels, with built-in tools, skills, and model execution; the catalogue entries extend or configure that workflow.
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 bubbuild/bub --skill skill-creatorgit clone --depth 1 https://github.com/bubbuild/bubWrote 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/bubbuild/bub/skill-creator)<a href="https://agentmods.dev/skills/bubbuild/bub/skill-creator"><img src="https://agentmods.dev/badge/skills/bubbuild/bub/skill-creator/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/bubbuild/bub/skill-creator"><img src="https://agentmods.dev/badge/skills/bubbuild/bub/skill-creator.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 | $0.00045 | $0.03851 |
| Opus 5.5 | $0.00018 | $0.01540 |
| Sonnet 5.5 | $0.00009 | $0.00770 |
| Haiku 4.5 | $0.00005 | $0.00385 |
Grade A, and why
skill-creator 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.
This is a copy
84% identical to skill-creator — 106 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 367 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Creator
This skill provides guidance for creating effective skills.
About Skills
Skills are modular, self-contained folders that extend Bub's capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform Bub from a general-purpose agent into a specialized agent equipped with procedural knowledge that no model can fully possess.
Skill Location Policy
When creating a skill, place it in one of these two roots:
- Project-local:
$workspace/.agents/skills/<skill-name> - Global:
~/.agents/skills/<skill-name>(shared across workspaces)
Prefer project-local by default. Use global only when the user explicitly wants the skill available across multiple workspaces.
What Skills Provide
- Specialized workflows - Multi-step procedures for specific domains
- Tool integrations - Instructions for working with specific file formats or APIs
- Domain expertise - Company-specific knowledge, schemas, business logic
- Bundled resources - Scripts, references, and assets for complex and repetitive tasks
Core Principles
Concise is Key
The context window is a public good. Skills share the context window with everything else Bub needs: system prompt, conversation history, other Skills' metadata, and the actual user request.
Default assumption: Bub is already very smart. Only add context Bub doesn't already have. Challenge each piece of information: "Does Bub really need this explanation?" and "Does this paragraph justify its token cost?"
Prefer concise examples over verbose explanations.
Set Appropriate Degrees of Freedom
Match the level of specificity to the task's fragility and variability:
High freedom (text-based instructions): Use when multiple approaches are valid, decisions depend on context, or heuristics guide the approach.
Medium freedom (pseudocode or scripts with parameters): Use when a preferred pattern exists, some variation is acceptable, or configuration affects behavior.
What ships with it
3 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.
- 1mo ago First seen · 367 lines · 45 tokens per session scan A b8456a091cb2
skill-creator is a skill published in the GitHub repository bubbuild/bub (1,686 stars, last pushed today), licensed Apache-2.0. It adds 45 tokens to every session and 3,851 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 84% identical to skill-creator, differing in 106 lines, and is treated as a copy.
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