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Agent skill

Retellai Hello World

by jeremylongshore in jeremylongshore/tons-of-skills-marketplace

Retell AI hello world — AI voice agent and phone call automation.

MITAuto-check passedAI & LLM Engineering

Install Retellai Hello World

skills CLI
$ npx skills add jeremylongshore/tons-of-skills-marketplace --skill retellai-hello-world -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install jeremylongshore/tons-of-skills-marketplace retellai-hello-world --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/jeremylongshore/tons-of-skills-marketplace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/.curated/retellai-hello-world .claude/skills/retellai-hello-world && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
retellai-hello-world
GitHub stars
2.8k
Token cost
~955 tokens
SKILL.md length
216 words
Files
1
Skills in repo
3,342
Repo updated
First seen
Licence
MIT

At a glance

Retell AI hello world — AI voice agent and phone call automation.

  • Works in 5 steps: Create an LLM Configuration → Create a Voice Agent → Make a Test Phone Call → …
  • Working with Retell AI for voice agents
  • SKILL.md covers Overview, Prerequisites, Instructions and Output, plus 4 more sections
  • Needs RETELL_API_KEY

What it does

Retellai Hello World is an agent skill from jeremylongshore/tons-of-skills-marketplace. Retell AI hello world — AI voice agent and phone call automation. Use when working with Retell AI for voice agents, phone calls, or telephony. Trigger with phrases like "retell hello world", "retellai-hello-world", "voice agent".

Its SKILL.md is about 960 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Designed for Claude Code

It sits in AI & LLM Engineering, covering Speech recognition and synthesis. The repository describes itself as: Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com. The licence is MIT.

When your agent uses it

  • Working with Retell AI for voice agents
  • With phrases like retell hello world
  • Retellai-hello-world

Example prompts

  • “retell hello world”
  • “retellai-hello-world”
  • “voice agent”
  • “/retellai-hello-world”

Requirements

  • A credential in RETELL_API_KEY
  • Compatibility (from SKILL.md): Designed for Claude Code
  • Pre-approved tools (allowed-tools): Read, Write, Edit, Bash(npm:*), Bash(curl:*), Grep

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Create an LLM Configuration
  2. Create a Voice Agent
  3. Make a Test Phone Call
  4. Or Test with Web Call
  5. Check Call Status

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Write
    • Edit
    • Bash(npm:*)
    • Bash(curl:*)
    • Grep

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • docs.retellai.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • RETELL_API_KEY

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    Designed for Claude Code

    From compatibility in the SKILL.md frontmatter.

Context cost

Retellai Hello World loads about 955 tokens when it runs. Until then it costs about 63 tokens; SKILL.md has 216 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~63
When it runs · the whole SKILL.md, loaded when a task matches
~955

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 216 words, ~955 tokens.

Download SKILL.mdSave it as .claude/skills/retellai-hello-world/SKILL.md (or your agent's skills folder).
name
retellai-hello-world
description
Retell AI hello world — AI voice agent and phone call automation. Use when working with Retell AI for voice agents, phone calls, or telephony. Trigger with phrases like "retell hello world", "retellai-hello-world", "voice agent".
allowed-tools
Read, Write, Edit, Bash(npm:*), Bash(curl:*), Grep
compatibility
Designed for Claude Code
version
1.9.0
license
MIT
author
Jeremy Longshore <jeremy@intentsolutions.io>
tags
saas, retellai, voice, telephony, ai-agents

Retell AI Hello World

Overview

Create your first Retell AI voice agent and make a test phone call.

Prerequisites

  • Completed retellai-install-auth
  • A phone number registered in Retell AI Dashboard (or use web call for testing)

Instructions

Step 1: Create an LLM Configuration
typescript
import Retell from 'retell-sdk';
const retell = new Retell({ apiKey: process.env.RETELL_API_KEY! });

// Create LLM configuration (what the agent says)
const llm = await retell.llm.create({
  model: 'gpt-4o',
  general_prompt: `You are a friendly receptionist for Acme Corp.
    - Greet callers warmly
    - Ask how you can help
    - Take messages if needed
    - Be concise and professional`,
});
console.log(`LLM created: ${llm.llm_id}`);
Step 2: Create a Voice Agent
typescript
const agent = await retell.agent.create({
  response_engine: {
    type: 'retell-llm',
    llm_id: llm.llm_id,
  },
  voice_id: '11labs-Adrian',  // Choose from available voices
  agent_name: 'Acme Receptionist',
});
console.log(`Agent created: ${agent.agent_id}`);
Step 3: Make a Test Phone Call
typescript
// Outbound call (requires a registered phone number)
const call = await retell.call.createPhoneCall({
  from_number: '+14155551234',  // Your Retell number
  to_number: '+14155555678',    // Destination
  override_agent_id: agent.agent_id,
});
console.log(`Call initiated: ${call.call_id}`);
Step 4: Or Test with Web Call
typescript
// Web call (no phone number needed — great for testing)
const webCall = await retell.call.createWebCall({
  agent_id: agent.agent_id,
});
console.log(`Web call URL: ${webCall.call_id}`);
// Use retell-client-js-sdk to connect from browser
Step 5: Check Call Status
typescript
const callDetail = await retell.call.retrieve(call.call_id);
console.log(`Status: ${callDetail.call_status}`);
console.log(`Duration: ${callDetail.end_timestamp - callDetail.start_timestamp}ms`);
if (callDetail.transcript) {
  console.log(`Transcript: ${callDetail.transcript}`);
}

Output

  • LLM configuration with custom prompt
  • Voice agent with selected voice
  • Test call initiated (phone or web)
  • Call status and transcript retrieved

Error Handling

ErrorCauseSolution
422 Invalid voice_idUnknown voiceList available voices in Dashboard
400 No phone numberNumber not registeredRegister number in Dashboard first
Call not connectingDestination unreachableTry web call for testing

Examples

Validate a first agent with a web call before using a phone number

Create a development agent with a short greeting and no external tools, then exercise it through the web-call interface using synthetic inputs. Confirm the selected voice, expected greeting, disconnect behavior, and redacted transcript. Only after this evidence is reviewed should a team attach a test phone number; production routing remains separate until the agent has a versioned preview and a documented fallback path.

Resources

Next Steps

Configure agent behavior: retellai-core-workflow-a

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/.curated/retellai-hello-world of jeremylongshore/tons-of-skills-marketplace.

Open the folder on GitHubat commit cfae287

Compare with similar skills

Retellai Hello World next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Retellai Hello World compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Retellai Hello World this skilljeremylongshore/tons-of-skills-marketplace2.8k—~955Automated safety check: PassMIT
TriageTalAter/annyang6.8k—~810Automated safety check: NotesMIT
Yichen Asrmcncarl/yichen-skills4.4k—~780Automated safety check: PassCustom licence
Dingtalk MinutesDingTalk-Real-AI/dingtalk-workspace-cli3.2k—~2.3kAutomated safety check: PassApache-2.0
Youtube FetcherJimmySadek/youtube-fetcher-to-markdown485—~3.1kAutomated safety check: PassMIT
Yichen Web Researchmcncarl/yichen-skills4.4k—~1.9kAutomated safety check: PassCustom licence

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Categories

Questions about Retellai Hello World

What does Retellai Hello World do?

Retell AI hello world — AI voice agent and phone call automation. Retellai Hello World is an agent skill from jeremylongshore/tons-of-skills-marketplace. Retell AI hello world — AI voice agent and phone call automation.

When should I use Retellai Hello World?

Retellai Hello World fits situations like: working with Retell AI for voice agents; with phrases like retell hello world; retellai-hello-world.

How do I install Retellai Hello World in Claude Code?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill retellai-hello-world -a claude-code`. Or copy the skill folder (skills/.curated/retellai-hello-world in jeremylongshore/tons-of-skills-marketplace) into .claude/skills/retellai-hello-world in your project. Claude Code loads it when a task matches its description.

How do I install Retellai Hello World in Codex?

Run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill retellai-hello-world -a codex`. Or copy the skill folder (skills/.curated/retellai-hello-world in jeremylongshore/tons-of-skills-marketplace) into .agents/skills/retellai-hello-world in your project. Codex loads it when a task matches its description.

Can I use Retellai Hello World in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add jeremylongshore/tons-of-skills-marketplace --skill retellai-hello-world -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/retellai-hello-world, .gemini/skills/retellai-hello-world, .github/skills/retellai-hello-world and .opencode/skills/retellai-hello-world in your project.

What does Retellai Hello World need to run?

Going by SKILL.md and its folder, Retellai Hello World needs credentials named RETELL_API_KEY. Our summary lists: A credential in RETELL_API_KEY. Its frontmatter pre-approves these tools: Read, Write, Edit, Bash(npm:*), Bash(curl:*), Grep. Compatibility (from SKILL.md): Designed for Claude Code.

Does Retellai Hello World access the network?

SKILL.md names 1 domain. As links in the text: docs.retellai.com. This is read from the text; nothing was executed.

Is Retellai Hello World safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Retellai Hello World use?

Retellai Hello World is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Retellai Hello World use?

About 955 tokens (SKILL.md is roughly 3.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Retellai Hello World?

Skills that share tags, products or a category with Retellai Hello World: Triage (TalAter/annyang, 6.8k stars), Yichen Asr (mcncarl/yichen-skills, 4.4k stars), Dingtalk Minutes (DingTalk-Real-AI/dingtalk-workspace-cli, 3.2k stars) and Youtube Fetcher (JimmySadek/youtube-fetcher-to-markdown, 485 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Retellai Hello World?

jeremylongshore (a GitHub user) maintains it in jeremylongshore/tons-of-skills-marketplace, which has 2,827 GitHub stars. The repository holds 3,342 skills in this directory. The repository was last updated on October 10, 2026.

Source: jeremylongshore/tons-of-skills-marketplace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.