Your AgentCore CLI is out of date (found vX.Y.Z, need v0.9.0+).
Offer to run the update: agentcore update. After the update completes, re-check the version to confirm it’s ≥0.9.0 before continuing. Preserve any context the developer already provided (framework preference, project name, what they want to build) so they don’t have to repeat themselves.
If agentcore is not found:
The AgentCore CLI isn’t installed. Run npm install -g @aws/agentcore (requires Node.js 20+).
If you’re having trouble with installation, I can run the agents-debug skill (which loads references/doctor.md (opens in a new tab)) to diagnose your environment.
Before jumping into framework selection, figure out where the developer is:
Ask the developer: “Are you exploring options (comparing frameworks, understanding what AgentCore does) or ready to create a project?”
Exploring → Go to Step 2 (framework comparison). Present the options, answer questions, and wait. Do not construct a create command until they signal they’re ready.
Ready to create → Skip to Step 3 (create the project). If they already specified a framework, skip Step 2 entirely.
Already has a project → Look for agentcore/agentcore.json in the current directory. If found, read it and skip to Step 5 (what to do next). Don’t re-scaffold.
If the developer’s intent is clear from $ARGUMENTS (e.g., “create a Strands agent called MyBot”), skip straight to Step 3.
Check conversation context first. If the developer already discussed frameworks earlier in this conversation (e.g., from a previous skill invocation), don’t re-present the full table. Summarize what was discussed and ask if they’ve decided, or if anything changed.
If this is the first time discussing frameworks, present the options:
Supported frameworks (CLI-scaffolded, Python):
Framework
CLI value
Best for
Strands
Strands
AWS-native, simplest path, best AgentCore integration
Ask the developer to choose. Present the options and wait for their selection. Don’t assume a default unless they explicitly say they have no preference.
Note on naming: The CLI flag value is the exact string to pass to --framework. In prose use the shorter names.
Default recommendation (only when the developer says “no preference” or “you pick”): Strands — AWS-native framework with the tightest AgentCore integration and the most samples/docs.
Key decision points to surface:
“Do you have existing agent code in LangGraph or OpenAI Agents?” → use that framework
“Do you need complex graph-based workflows with conditional branching?” → LangGraph
If the developer asks about a framework not in the table above, handle it:
They ask about
What to say
CrewAI, AutoGen, Semantic Kernel
Not scaffolded by the CLI, but you can use them via the BYO Container path (below). AgentCore Runtime is framework-agnostic — any code that implements the HTTP contract works.
Anthropic SDK / Claude Agent SDK
This is a model SDK, not an agent framework. You can use it inside any framework (Strands, LangGraph, etc.) or standalone. For standalone use, wrap it in a container with the Runtime contract.
Claude Code / Cursor / Copilot
These are IDE tools, not agent frameworks. They’re where you write agent code, not what you deploy. Pick a framework from the table above for the agent itself.
LangChain (without LangGraph)
LangChain is a library, LangGraph is the agent framework built on it. The CLI scaffolds LangGraph. If you’re using plain LangChain chains, the BYO Container path works.
Custom / homegrown framework
BYO Container path — see below.
BYO Container path (any framework, any language):
For frameworks or languages not scaffolded by the CLI, AgentCore Runtime accepts any container that implements the HTTP contract (POST /invocations, GET /ping). The workflow:
agentcore create --name <ProjectName> --defaults to scaffold the project structure
agentcore add agent --type byo --build Container --language <Language> --code-location <path> to register your code
Write a Dockerfile that builds and runs your agent
agentcore deploy handles ECR push, CDK infra, and runtime creation
The framework is how your agent orchestrates (Strands, LangGraph, etc.). The model provider is which LLM it calls (Bedrock, Anthropic, OpenAI, Gemini). These are independent choices:
Strands + Anthropic — Strands orchestration, direct Anthropic API for the model
LangGraph + Bedrock — LangGraph orchestration, Bedrock for the model
OpenAI Agents + OpenAI — OpenAI everything
If the developer says “I want to use Claude” they mean the model provider (Bedrock or Anthropic), not the framework. If they say “I want to use LangGraph” they mean the framework.
Build the agentcore create command based on the developer’s choices.
Before constructing the command — validate the project name. The CLI fails late: if the name is invalid, you’ll see the error after walking through prompts or building the full command. Save the round-trip and check these rules up front. Reject the name and ask for a new one if any rule fails:
Length ≤ 23 characters (this is shorter than most developers assume — MyCustomerSupportAgent is 22 chars and fits; CustomerSupportChatbot is 22 and fits; MyCustomerSupportBotApp is 23 and just fits; MyCustomerSupportChatBot is 24 and fails)
Alphanumeric only — no hyphens, underscores, dots, or spaces
Must start with a letter
Say the count back out loud when close to the limit: “That name is 24 characters — the CLI caps project names at 23. Want to shorten it to <suggestion>?” Do not run the command with an invalid name on the assumption that the CLI error message will be clear — it isn’t always, and the developer’s mental model will be wrong for subsequent commands.
Construct the command, then present it for confirmation before the developer runs it. Show the full command with all flags and explain what each choice means. Wait for the developer to confirm or adjust before proceeding.
Example presentation:
Here’s the command I’d recommend based on what you’ve told me:
After the project exists, read agentcore/agentcore.json and the generated code to explain the project structure.
The layout below reflects CLI v0.9.x. If the CLI version is different, run tree <ProjectName>/ -L 3 to see the actual generated structure and explain from there.
<ProjectName>/├── agentcore/│ ├── agentcore.json ← Project config (agents, resources)│ ├── aws-targets.json ← AWS account + region│ ├── .env.local ← Local environment variables (gitignored)│ └── cdk/ ← CDK infrastructure (auto-managed, don't edit)└── app/ └── <AgentName>/ ├── main.py ← Your agent code — this is where you build ├── mcp_client/ ← Pre-wired example MCP client (see note below) └── pyproject.toml ← Python dependencies
Key files to highlight:
app/<AgentName>/main.py — the agent’s entry point. This is where the developer adds tools, system prompts, and logic.
agentcore/agentcore.json — the project config. Resources are added here via agentcore add commands.
agentcore/.env.local — local environment variables. After deploy, resource IDs are written here for local dev.
Heads-up on the scaffolded MCP client.main.py imports get_streamable_http_mcp_client() from mcp_client/client.py and appends it to tools. In a fresh project, this client points at a public example MCP endpoint — so agentcore dev works immediately. Two things to flag:
It will become a silent no-op if you repoint it at a gateway that isn’t deployed yet. The common path is to swap the example endpoint for os.getenv("AGENTCORE_GATEWAY_<NAME>_URL"). That env var is only populated after agentcore deploy. If the developer repoints and runs agentcore dev before deploying, get_streamable_http_mcp_client() returns a client with a None URL and the agent starts with zero MCP tools — no error, no warning. See the “Local dev gap” section in agents-connect for the guard pattern: if not GATEWAY_URL: tools = [].
If the developer doesn’t need MCP tools at all, remove the mcp_clients list and the loop that appends it to tools. The scaffold includes it as a convenience, not a requirement.
The reference client code in agents-connect (Path A) shows the correct pattern for gateway-backed MCP clients once deploy has run.
This starts a local dev server. The developer can interact with their agent immediately.
Port the dev server binds to (important if you’re scripting curl calls or testing from another process):
Protocol
Default port
HTTP
8080
MCP
8000
A2A
9000
The CLI prints the bound port and URL on startup — always read the actual value from the CLI output rather than hardcoding. If the default port is already in use, the CLI auto-increments (e.g., 8080 → 8081 → 8082), so a second dev session or a lingering process from a previous run can shift your port without warning. Use agentcore dev --port <N> to pin it, or grep ps / check the CLI banner if invocations start failing with connection-refused or exit-code-7 errors.
Important limitations to mention:
Memory is not available in agentcore dev — it requires a deploy
Gateway URLs are not available locally — they require a deploy
The local server uses the model provider configured in the project
Skills install per repository, not per chapter — the CLI has no documented per-skill form, so we do not print one.
About this skill
Trigger
Use when a developer wants to create a new agent project or get started with AgentCore. Handles framework selection, project scaffolding, first deploy, and first invocation. Triggers on: "build an agent", "create an agent", "get started", "new project", "agentcore create", "which framework", "Strands vs LangGraph", "hello world agent", "first agent", "create MCP server", "host MCP server", "agentcore dev", "dev server", "what port", "local development". Not for adding capabilities to existing projects — use agents-build or agents-connect. Strands vs LangGraph in a migration context routes to agents-build, not here. Connecting to an existing MCP server routes to agents-connect, not here.
The verbatim description from this skill’s front matter — the string an agent matches on to decide whether to load it.
Apache-2.0 — the text of every chapter is reproduced unmodified, frontmatter included, under the upstream licence.
Discovery
118 chapters found by walking the repository tree for SKILL.md, not by matching a directory convention. 16 distinct layouts observed: plugins/aws-agents-for-devsecops/skills/*/SKILL.md, plugins/aws-agents/skills/*/SKILL.md, plugins/aws-core/skills/*/SKILL.md, skills/core-skills/*/SKILL.md, skills/specialized-skills/analytics-skills/*/SKILL.md, skills/specialized-skills/database-skills/*/SKILL.md, skills/specialized-skills/ec2-skills/*/SKILL.md, skills/specialized-skills/migration-and-modernization-skills/*/SKILL.md, skills/specialized-skills/networking-and-content-delivery-skills/*/SKILL.md, skills/specialized-skills/operations-skills/*/SKILL.md, skills/specialized-skills/resilience-skills/*/SKILL.md, skills/specialized-skills/security-and-identity-skills/*/SKILL.md, skills/specialized-skills/serverless-skills/*/SKILL.md, skills/specialized-skills/storage-skills/*/SKILL.md, skills/specialized-skills/system-table-skills/*/SKILL.md, skills/specialized-skills/web-and-mobile-development/*/SKILL.md.
Duplicates collapsed
28 mirror copies folded into their canonical chapter — republished for Alternate. Copies match on content hash and on position once a leading per-agent prefix is stripped, because the same skill is routinely shipped under a dozen agent directories with a dozen different hashes.
Issue colours
Resolved from a curated brand profile — hue 65°, chroma 0.174. Two accent tones are generated per issue and each is proven against its own ground before it ships: a single accent that passes AA on both light and dark paper is arithmetically impossible.
Heading repairs
1 repair applied to this chapter so the document has one h1 and no skipped levels:
Shifted “17 headings” from h1 to h2 so the chapter title is the only h1.
Images inside a chapter come from the upstream repository. Where the author gave no alternative text we mark the image decorative rather than inventing a description — a plausible caption we made up is worse than none for the reader who depends on it.
Marketplace
A plugin manifest is published at .claude-plugin/marketplace.json by Amazon Web Services, declaring 4 plugins. It is read for editorial metadata only — never as the skill index, which is always the repository tree.
Signal
Install counts come from skills.sh. They measure downloads, not quality, and an unranked repository is not an unread one.
Agent surfaces
The whole issue is available as one markdown document at /aws/agent-toolkit-for-aws.md, and each chapter at its own .md URL.
Publication
Set by Skills Docs from the source repository. Body text is Literata at the reader’s chosen size and measure; code is Geist Mono. Nothing on this page was written by us except this paragraph.
Appendix 18.1
1 file · 7 KB
Everything this skill ships beside its prose. All of it is set here, as a subchapter of chapter 18.
ReferencesMarkdown · 1 file
Documentation the agent loads on demand, rather than up front.