Borrowing it
Nothing to install: this file belongs to strands-compose/sdk-python. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/strands-compose/sdk-python/main/.kiro/skills/library-development/SKILL.mdgit clone --depth 1 https://github.com/strands-compose/sdk-pythonWrote 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/strands-compose/sdk-python/library-development)<a href="https://agentmods.dev/skills/strands-compose/sdk-python/library-development"><img src="https://agentmods.dev/badge/skills/strands-compose/sdk-python/library-development/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/strands-compose/sdk-python/library-development"><img src="https://agentmods.dev/badge/skills/strands-compose/sdk-python/library-development.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 | $0.00070 | $0.04158 |
| Opus 5.5 | $0.00028 | $0.01663 |
| Sonnet 5.5 | $0.00014 | $0.00832 |
| Haiku 4.5 | $0.00007 | $0.00416 |
Grade A, and why
library-development 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 2mo 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 — 321 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Library Development
Rules for the strands-compose library in src/strands_compose/
(Python ≥ 3.11 + Pydantic v2 + strands-agents + PyYAML + MCP). They describe
the mental model and conventions, not the current set of files — sections,
providers, and orchestration modes come and go, the shape stays.
strands-compose does exactly one thing: read YAML and hand back fully wired,
plain strands objects — no wrappers, no subclasses. Everything agent-,
model-, session-, tool-, or MCP-related is provided by strands. Before building
anything that touches those, check the installed SDK
(.venv/lib/python*/site-packages/strands/) and use what it provides rather
than re-implementing it. When in doubt about upstream APIs, use the
strands-api-lookup skill.
Before creating anything new, read a sibling that plays the same role and copy
its shape. Matching the existing pattern matters more than any rule below. See
references/project-map.md for where each role lives and what to read first —
load it whenever you are unsure where something goes.
Core Principles — NON-NEGOTIABLE
- Strands-first — if strands provides it, import and use it directly; never re-implement it. This library is a translator, not a framework.
- Thin wrapper — translate YAML to strands objects, then get out of the way. Return plain
Agent/Swarm/Graph/Model/MCPClient, never a subclass or proxy. - The pipeline flows one way — text -> dict -> validated schema -> live objects. Never resolve during parsing; never parse during resolution (see The Pipeline).
- Explicit over implicit — no auto-registration, no global singletons, no hidden state. Every object is wired by hand and passed as an argument.
- Single responsibility — each module does one thing; one resolver per config concept, one builder per orchestration mode.
- Composition over inheritance — small functions and focused modules that compose. The only base classes are the strands-facing ones (e.g.
HookProvider). - Smallest reasonable change — don't refactor unrelated code to land a feature.
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.
- 2mo ago First seen · 321 lines · 70 tokens per session scan A a1268bf9e3d8
library-development is a skill published in the GitHub repository strands-compose/sdk-python (6 stars, last pushed 3d ago), licensed Apache-2.0. It adds 70 tokens to every session and 4,158 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-08-31.
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