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/mumez/smalltalk-dev-plugin/smalltalk-developernpx skills add mumez/smalltalk-dev-plugin --skill smalltalk-developergit clone --depth 1 https://github.com/mumez/smalltalk-dev-pluginWhat 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 | $0.00160 | $0.02426 |
| Opus 5 | $0.00080 | $0.01213 |
| Sonnet 5 | $0.00032 | $0.00485 |
| Haiku 4.5 | $0.00016 | $0.00243 |
Grade A, and why
smalltalk-developer 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 2d 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 — 305 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Smalltalk Developer Workflow
Implement the standard workflow for Smalltalk (Pharo or Squeak) development using AI editors and the Tonel file format.
Prerequisites
Before starting development, ensure the environment is ready:
- No project structure (no
src/or.project): Usesmalltalk-dev:st-setup-projectskill to create boilerplate - Smalltalk image not connected or session not initialized: Use
smalltalk-dev:st-initskill to verify connection and set up environment
Core Development Cycle
The fundamental workflow for Smalltalk development consists of three steps that repeat:
1. Edit Tonel Files
Edit Tonel files directly in the AI editor. The AI editor is the single source of truth for code.
Key principle: All code changes happen in .st files, not in the Smalltalk image.
Tonel basics:
- One class per
.stfile - File name matches class name
- Each package directory contains
package.st
For detailed Tonel syntax and examples, see Tonel Format Reference.
Follow the Style Guide for idiomatic Smalltalk.
Refer to Implementation Patterns for common patterns (Singleton, Settings, etc.).
2. Import to the Smalltalk Image
Before importing, run lint to check code quality:
/st-lint src/MyPackage # Check Smalltalk best practices
Then import the package into the running Smalltalk image using absolute paths:
mcp__smalltalk-interop__import_package: 'MyPackage' path: '/home/user/project/src'
Critical rules:
- ✅ Lint before import - Check code quality first
- ✅ Always use absolute paths (never relative)
- ✅ Re-import after every change
- ✅ Import packages in dependency order
- ✅ Import test packages after main packages
3. Run Tests
After import, run tests to verify changes:
mcp__smalltalk-interop__run_class_test: 'MyClassTest'
mcp__smalltalk-interop__run_package_test: 'MyPackage-Tests'
What ships with it
5 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.
- 2d ago First seen · 305 lines · 160 tokens per session scan A 5a4627782d7c
smalltalk-developer is a skill published in the GitHub repository mumez/smalltalk-dev-plugin (15 stars, last pushed 6d ago), licensed MIT. It adds 160 tokens to every session and 2,426 once invoked, about $0.0008 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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