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 synthesisengineering/synthesis-skills --skill synthesis-code-planninggit clone --depth 1 https://github.com/synthesisengineering/synthesis-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/synthesisengineering/synthesis-skills/synthesis-code-planning)<a href="https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-code-planning"><img src="https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-code-planning.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 | $0.00061 | $0.00693 |
| Opus 5 | $0.00030 | $0.00347 |
| Sonnet 5 | $0.00012 | $0.00139 |
| Haiku 4.5 | $0.00006 | $0.00069 |
Grade A, and why
synthesis-code-planning 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 7d 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 — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Code Planning
A structured methodology for approaching code tasks that produces higher-quality implementations by evaluating multiple approaches before committing to one.
Inputs
Before generating code, gather three inputs:
- Task description -- what needs to be built or changed
- Existing code -- the current codebase or relevant files (if any)
- Contextual documentation -- relevant API docs, framework guides, coding standards, or architectural decisions
Process
Step 1: Analyze
Carefully analyze the task description and existing code. Consider:
- What is the actual goal (not just the literal request)?
- What constraints does the existing code impose?
- What are the performance, maintainability, and correctness requirements?
- What best practices apply to this language, framework, or domain?
Step 2: Generate approaches
Produce at least two distinct approaches to address the task. For each approach, document:
Approach 1: [Brief description]
- Pros:
- [Advantage 1]
- [Advantage 2]
- Cons:
- [Drawback 1]
- [Drawback 2]
Approach 2: [Brief description]
- Pros:
- [Advantage 1]
- [Advantage 2]
- Cons:
- [Drawback 1]
- [Drawback 2]
Generate more approaches when the problem space is ambiguous or when the first two approaches have significant trade-offs against each other.
Step 3: Evaluate and select
Select the optimal solution and justify the choice with specific reasoning:
- Reference the pros and cons of each approach
- Explain why the chosen approach best addresses the task requirements
- Acknowledge what is sacrificed by not choosing the alternatives
- If the decision is close, state that explicitly
Step 4: Implement
Implement the chosen solution by modifying or creating code:
- Mark changes clearly when modifying existing code
- Follow the conventions and patterns already present in the codebase
- Optimize for performance, maintainability, and adherence to best practices
- Include necessary error handling and edge case coverage
What ships with it
1 file 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.
- 7d ago First seen · 87 lines · 61 tokens per session scan A ef0efb94adee
synthesis-code-planning is a skill published in the GitHub repository synthesisengineering/synthesis-skills (18 stars, last pushed today), licensed Apache-2.0. It adds 61 tokens to every session and 693 once invoked, about $0.0003 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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