Sample Agent Skills for Builders is a collection of reusable skills that extend AI coding agents with AWS, CDK, security, testing, and engineering workflows. Developers can install the skills for practical AWS development tasks or use the repository as a model for creating their own agent skills. The catalogue entries are skills and instructions from this collection.
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 aws-samples/sample-agent-skills-for-builders --skill strands-context-managergit clone --depth 1 https://github.com/aws-samples/sample-agent-skills-for-buildersWrote 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/aws-samples/sample-agent-skills-for-builders/strands-context-manager)<a href="https://agentmods.dev/skills/aws-samples/sample-agent-skills-for-builders/strands-context-manager"><img src="https://agentmods.dev/badge/skills/aws-samples/sample-agent-skills-for-builders/strands-context-manager/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/aws-samples/sample-agent-skills-for-builders/strands-context-manager"><img src="https://agentmods.dev/badge/skills/aws-samples/sample-agent-skills-for-builders/strands-context-manager.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00037 | $0.00436 |
| Opus 5.5 | $0.00015 | $0.00174 |
| Sonnet 5.5 | $0.00007 | $0.00087 |
| Haiku 4.5 | $0.00004 | $0.00044 |
Grade A, and why
strands-context-manager 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.
What it actually says
Strands Context Manager (Sliding Window with Summarization)
Strands Agents SDK conversation manager combining sliding window and summarization strategies.
When to Apply
Reference this skill when:
- Building Strands agents with long conversations
- Implementing context window management
- Preventing session pollution in multi-turn dialogs
- Combining sliding window with summarization
Critical Pitfalls
1. Inheritance Pitfall
DON'T inherit from SummarizingConversationManager.
DO inherit from base ConversationManager.
2. Infinite Recursion
Use _is_summarizing flag with try/finally to prevent recursion during summarization calls.
3. Hook Closure Problem (MOST CRITICAL)
Lambda closures capture session_manager references during initialization. Create summarization agent WITHOUT session_manager, hooks, or persistence.
Implementation Pattern
class SlidingWindowWithSummarizationManager(ConversationManager):
def __init__(self, window_size=40, summarization_agent=None, summarization_system_prompt=None):
self._is_summarizing = False
self._summarization_agent = summarization_agent # Lazy init when None
def _get_summarization_agent(self):
# Create clean agent without session_manager
return Agent(
# NO session_manager, NO hooks
)
Usage
from conversation_manager import SlidingWindowWithSummarizationManager
manager = SlidingWindowWithSummarizationManager(
window_size=20,
)
Critical Test
def test_no_session_pollution():
# Verify internal messages don't persist
# Verify no "Please summarize" in session
References
- Architecture - Detailed design and testing
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 · 70 lines · 37 tokens per session scan A 8f93e44d3e50
strands-context-manager is a skill published in the GitHub repository aws-samples/sample-agent-skills-for-builders (53 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 436 once invoked, about $0.0001 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 2026-08-30.
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