Api Expert by growthxai
Use this agent for Output.ai API server design, Express middleware configuration, workflow execution endpoints, and API security patterns. Specializes in workflow integration via REST APIs.
- Type
- Subagent
- Repository
- growthxai/output
- GitHub stars
- 439
- License
- Apache-2.0
- Repo last updated
- Sep 25, 2026
- Source file
- .claude/agents/api-expert.md
What Api Expert by growthxai is
Api Expert by growthxai is a subagent published in the growthxai/output repository on GitHub, which has about 439 stars. The repository describes itself as: “The open-source TypeScript framework for building AI workflows and agents. Designed for Claude Code describe what you want, Claude builds it, with all the best practices already in place.”
A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.
Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Api Expert and get back a compact result.
How to install Api Expert by growthxai
Claude Code
- Download api-expert.md from the repository.
- Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
- Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Claude Cowork
- Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
- Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.
Inside the source file
An excerpt from .claude/agents/api-expert.md, shared under the repository's Apache-2.0 license. Read the full file on GitHub.
Role Definition
You are an expert in API server development for the Output project, with deep knowledge of:
- Express server configuration and middleware
- Workflow execution API endpoints
- API security and error handling
Core Competencies
- Express Configuration: Middleware setup, CORS handling, request parsing
- Workflow APIs: Execution endpoints, status checking, result retrieval
- Error Handling: HTTP error responses, validation failures, timeout handling
- Security: Input validation, CORS policies, rate limiting
Output API Patterns
- Workflow Execution: Endpoint design and input validation (see api/README.md for current routes)
- Signal Handling: Workflow resumption and feedback processing
- Health Checks: Service monitoring and readiness probes
- Workflow Discovery: Listing available workflows with static file interpretation
- Temporal Integration: Client setup, workflow starting, signal sending
Express Best Practices
- Middleware Chain: Request validation, error handling, response formatting
- Route Organization: Endpoint grouping, parameter handling
- Async Patterns: Promise-based request handling, error propagation
- Response Formatting: Consistent JSON responses, error structures
Response Guidelines
- Focus on Express patterns specific to workflow APIs
- Consider workflow lifecycle management through REST endpoints
- Emphasize proper error handling and client feedback
- Reference api/README.md for current endpoint documentation
- Provide examples from api/src/index.js patterns
- Consider scalability and production deployment needs
Common API Scenarios
- Workflow Lifecycle: Start, monitor, signal, terminate workflows
- Workflow Discovery: List available workflows with static file interpretation
- Batch Operations: Multiple workflow execution, status polling
- Error Recovery: Retry mechanisms, failure notifications
- Integration Patterns: Webhook callbacks, external system integration
Before you install
- Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
- Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
- Try it in a test project or a copy of your files before pointing it at real work.
- Pin the version you tested, and review changes before updating.
- Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.
FAQ
What is Api Expert by growthxai?
Api Expert by growthxai is a subagent for Claude Code and Claude Cowork from the growthxai/output repository on GitHub. Use this agent for Output.ai API server design, Express middleware configuration, workflow execution endpoints, and API security patterns. Specializes in workflow integration via REST APIs.
How do I install Api Expert by growthxai in Claude Code?
Download api-expert.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Can I use Api Expert by growthxai in Claude Cowork?
Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
Is Api Expert by growthxai safe to install?
It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.
Similar resources
- Workflow Debugger Use this agent when you need to debug Output SDK workflows in local development. Invoke when workflows fail, return unexpected results, or you need to analyze execution traces to identify root causes. Subagent · growthxai/output
- Workflow Context Fetcher Use proactively to retrieve and extract relevant information from Output SDK project documentation files. Checks if content is already in context before returning. Subagent · growthxai/output
- Workflow Planner Design new workflows for the Output SDK system, plan complex workflow orchestrations, or create comprehensive implementation blueprints. Use at the beginning of workflow development to ensure proper architecture and complete requirements gathering. Subagent · growthxai/output
- Testing Expert Use this agent for Output.ai testing strategies including Vitest configuration, Temporal workflow testing, LLM mocking, integration testing, and test performance optimization. Specializes in JavaScript testing patterns with Output.ai abstractions. Subagent · growthxai/output
- Docker Expert Use this agent for Output.ai containerization including Docker Compose configuration, Node.js container optimization, Temporal service orchestration, and development environment setup. Specializes in Output deployment patterns. Subagent · growthxai/output
- Robot Tech Lead Tech lead for Java Enterprise Development. Creates plans or OpenSpec changes independently, then coordinates delivery through the… Subagent · jabrena/plinth
- Llm Expert Use this agent for AI SDK integration, LLM provider configuration, prompt template management, error handling for AI APIs, and optimizing LLM workflow patterns within Output. Specializes in Anthropic Claude and OpenAI integrations. Subagent · growthxai/output
- Robot No Java Default implementation specialist for non-Java projects. Use when an issue, plan, or OpenSpec task list does not use Java, Maven, or a… Subagent · jabrena/plinth