serverless-cold-starts

serverless-cold-starts is a skill for Claude Code, Codex from j4flmao/agent-skills. It costs 0 tokens per session (368 once invoked), scanned A, original, MIT.

A guide to reducing serverless cold starts: the delay while a cloud function, such as AWS Lambda or Azure Functions, creates and prepares a new execution environment.

In plain words
What is it for?
Use it to optimize serverless function startup, choose runtime settings, and balance latency against cloud spending.
Why use it?
It helps explain why the first request can be slower and how startup work, dependencies, connections, and pre-warmed environments affect response time and cost.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to optimize serverless function startup, choose runtime settings, and balance latency against cloud spending.

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Install with agentmods
npx agentmods add skills/j4flmao/agent-skills/serverless-cold-starts
Install

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.

Any agent
npx skills add j4flmao/agent-skills --skill serverless-cold-starts
Clone the repo
git clone --depth 1 https://github.com/j4flmao/agent-skills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for serverless-cold-starts

README.md
[![agentmods](https://agentmods.dev/badge/skills/j4flmao/agent-skills/serverless-cold-starts/github.svg)](https://agentmods.dev/skills/j4flmao/agent-skills/serverless-cold-starts)
Your own site
<a href="https://agentmods.dev/skills/j4flmao/agent-skills/serverless-cold-starts"><img src="https://agentmods.dev/badge/skills/j4flmao/agent-skills/serverless-cold-starts/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.

agentmods 80×15 button for serverless-cold-starts

Your own site · 80×15
<a href="https://agentmods.dev/skills/j4flmao/agent-skills/serverless-cold-starts"><img src="https://agentmods.dev/badge/skills/j4flmao/agent-skills/serverless-cold-starts.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 368 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00368
Opus 5 $0.00000 $0.00184
Sonnet 5 $0.00000 $0.00074
Haiku 4.5 $0.00000 $0.00037

Measured 8d ago against content hash 44c398d02610, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

serverless-cold-starts 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 8d 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.

skills/cloud-native/serverless-cold-starts/SKILL.md · 27 lines

What it actually says

Serverless Cold Starts & Optimization

1. Skill Context

Focus: Execution environment lifecycle, AWS Lambda/Azure Functions, provisioned concurrency, and runtime optimization. Triggers: lambda cold start, optimize serverless, provisioned concurrency, aws lambda performance

2. Deep Optimization Mechanics

The agent must understand the micro-vm (Firecracker) initialization sequence and runtime constraints.

The Cold Start Anatomy

  1. Infrastructure Phase: Cloud provider allocates a micro-VM, downloads the code package, and bootstraps the runtime.
  2. Init Phase: The runtime loads the user code and executes code outside the main handler function.
  3. Invoke Phase: The actual handler function processes the event.

Mitigation Strategies

  • Provisioned Concurrency: Keeping a specific number of execution environments pre-warmed. Explain the cost implications versus latency requirements.
  • Init Phase Optimization:
    • Lazy loading dependencies (importing modules inside the handler if they are rarely used).
    • Establishing database connections outside the handler so they are preserved across warm invocations.
  • Language & Runtime Selection: Transitioning from heavy runtimes (Java/Spring, C#) to fast-booting compiled languages (Go, Rust) or leveraging AOT (Ahead-of-Time) compilation like GraalVM native images.
  • VPC Cold Starts: Explaining how modern AWS Lambda Hyperplane ENIs solved the historic VPC cold start issue, but why IP address exhaustion is still a concern.

3. Output Format

  • Provide architecture strategies for multi-tier serverless apps.
  • Detail code-level refactoring to shift heavy initialization out of the critical path.
  • Provide Terraform snippets for configuring Provisioned Concurrency and Auto Scaling.
Files

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.

Changes

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.

  1. 8d ago First seen · 27 lines · 0 tokens per session scan A 44c398d02610

Subscribe to this mod's changes

serverless-cold-starts is a skill published in the GitHub repository j4flmao/agent-skills (23 stars, last pushed 5d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 368 tokens. 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 2026-09-03.

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