agents-sdk

Development guidance for building AI agents on Cloudflare Workers with the Agents SDK, including stored state, scheduled work, workflows, WebSockets, chat, and MCP connections.

In plain words
What is it for?
Use it when creating stateful agents, durable multi-step workflows, real-time or scheduled applications, chat apps, MCP clients or servers, and React clients that connect to agents.
Why use it?
The SDK documentation can change, so the instructions direct the agent to retrieve the current topic-specific documentation before implementing anything.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/lfyxhappy/lfcode/agents-sdk
Any agent
npx skills add lfyxhappy/lfcode --skill agents-sdk
Clone the repo
git clone --depth 1 https://github.com/lfyxhappy/lfcode

Made for: Claude Code, Codex.

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,475 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00059 $0.01475
Opus 5 $0.00030 $0.00737
Sonnet 5 $0.00012 $0.00295
Haiku 4.5 $0.00006 $0.00147

Measured yesterday against content hash 6769c6520383, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agents-sdk 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 yesterday.

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.

Origin

This is a copy

100% identical to agents-sdk — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

packages/lfcode/test/fixture/skills/agents-sdk/SKILL.md · 153 lines

How it starts

The opening of the file, as written. The whole thing — 153 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cloudflare Agents SDK

STOP. Your knowledge of the Agents SDK may be outdated. Prefer retrieval over pre-training for any Agents SDK task.

Documentation

Fetch current docs from https://github.com/cloudflare/agents/tree/main/docs before implementing.

Topic Doc Use for
Getting started docs/getting-started.md First agent, project setup
State docs/state.md setState, validateStateChange, persistence
Routing docs/routing.md URL patterns, routeAgentRequest, basePath
Callable methods docs/callable-methods.md @callable, RPC, streaming, timeouts
Scheduling docs/scheduling.md schedule(), scheduleEvery(), cron
Workflows docs/workflows.md AgentWorkflow, durable multi-step tasks
HTTP/WebSockets docs/http-websockets.md Lifecycle hooks, hibernation
Email docs/email.md Email routing, secure reply resolver
MCP client docs/mcp-client.md Connecting to MCP servers
MCP server docs/mcp-servers.md Building MCP servers with McpAgent
Client SDK docs/client-sdk.md useAgent, useAgentChat, React hooks
Human-in-the-loop docs/human-in-the-loop.md Approval flows, pausing workflows
Resumable streaming docs/resumable-streaming.md Stream recovery on disconnect

Cloudflare docs: https://developers.cloudflare.com/agents/

Capabilities

The Agents SDK provides:

  • Persistent state - SQLite-backed, auto-synced to clients
  • Callable RPC - @callable() methods invoked over WebSocket
  • Scheduling - One-time, recurring (scheduleEvery), and cron tasks
  • Workflows - Durable multi-step background processing via AgentWorkflow
  • MCP integration - Connect to MCP servers or build your own with McpAgent
  • Email handling - Receive and reply to emails with secure routing
  • Streaming chat - AIChatAgent with resumable streams
  • React hooks - useAgent, useAgentChat for client apps

Read the full file on GitHub · 153 lines

Files

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.

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. yesterday First seen · 153 lines · 59 tokens per session scan A 6769c6520383

Subscribe to this mod's changes

agents-sdk is a skill published in the GitHub repository lfyxhappy/lfcode (2 stars, last pushed 1mo ago), licensed MIT. It adds 59 tokens to every session and 1,475 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to agents-sdk, differing in 0 lines, and is treated as a copy.