Justworks MCP Server
for AI Agents
Connect your AI agent to StackOne's Justworks MCP server and give it 21 MCP tools out of the box. Auth, tool execution, and security all managed.
StackOne 
Coverage
21 Agent Actions
Create, read, update, and delete across Justworks — and extend your agent's capabilities with custom actions.
Authentication
Agent Tool Authentication
Per-user OAuth in one call. Your Justworks MCP server gets session-scoped tokens with zero credentials stored on your infra.
Agent Auth →
Security
Agent Protection
Every Justworks tool response scanned for prompt injection in milliseconds — 88.7% accuracy, all running on CPU.
Prompt Injection Defense →
Performance
Max Agent Context. Min Cost.
Free up to 96% of your agent's context window to enhance reasoning and reduce cost, on every Justworks call.
Tools Discovery →What is the Justworks MCP Server?
A Justworks MCP server lets AI agents read and write Justworks data through the Model Context Protocol — Anthropic's open standard for connecting LLMs to external tools. StackOne's Justworks MCP server ships with 21 pre-built actions, fully extensible via the Connector Builder — plus managed authentication, prompt injection defense, observability, and agent execution runtime. Connect it from MCP clients like Claude Desktop, Claude Code, Cursor, Goose, and VS Code, or from agent frameworks like OpenAI Agents SDK, LangChain, and Vercel AI SDK.
All Justworks MCP Tools
Every action from Justworks's API, ready for your agent. Create, read, update, and delete — scoped to exactly what you need.
Members
- List Members
Retrieve a paginated list of company members (employees and contractors).
- Get Member
Retrieve a specific member by their ID.
Deductions
- Create Deductions
Create new deductions for company members.
- List Deductions
Retrieve a paginated list of deductions.
- Update Deductions
Update existing deductions.
Time Off Balances Reports
- Create Time Off Balances Report
Create a new time off balances report.
- Get Time Off Balances Report
Retrieve a previously created time off balances report.
Other (14)
- Get Company
Retrieve company information including name, addresses, departments, and offices.
- Get Company Bank Account
Retrieve company bank account details.
- Get Company Business Info
Retrieve company business information including entity identifiers and officers.
- List Company Custom Fields
Retrieve all custom fields defined for the company.
- List Company Jurisdictions
Retrieve all jurisdictions where the company operates.
- List Member Custom Field Values
Retrieve custom field values for a specific member.
- List Payrolls
Retrieve a paginated list of payrolls.
- List Payroll Fees
Retrieve fees associated with a specific payroll.
- List Payroll Paystubs
Retrieve paystubs for a specific payroll.
- Get Paystub
Retrieve a specific paystub by its ID.
- List Deduction Types
Retrieve all available deduction types.
- List Time Off Policies
Retrieve a paginated list of time off policies.
- List Time Off Requests
Retrieve a paginated list of time off requests.
- Cancel Deductions
Cancel existing deductions.
Justworks AI Agent Use Cases
Connect your AI agent to Justworks and help your team scale the HR operations they run by hand today.
Use StackOne to connect your AI agent to your HRIS, identity management, and LMS to automate employee onboarding.
ViewUse StackOne to connect your AI agent to your HRIS, knowledge base, and messaging tools to automate HR policy Q&A.
ViewUse StackOne to connect your AI agent to your HRIS, identity management, and ITSM to automate employee offboarding and deprovisioning.
ViewSet Up Your Justworks MCP Server in Minutes
One endpoint. Any framework. Your agent is talking to Justworks in under 10 lines of code.
Agent Frameworks
JSON{
"mcpServers": {
"stackone": {
"command": "npx",
"args": [
"-y",
"mcp-remote@latest",
"https://api.stackone.com/mcp?x-account-id=<account_id>",
"--header",
"Authorization: Basic <YOUR_BASE64_TOKEN>"
]
}
}
}Check More HRIS / HCM MCP Servers
162+ actions
128+ actions
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123+ actions
120+ actions
117+ actions
111+ actions
Platform Resources
MCP Code Mode: Keeping Tool Responses Out of Agent Context
Anthropic's code_execution processes data already in context. Custom MCP code mode keeps raw tool responses in a sandbox. 14K tokens vs 500.
11 min
Comparing BM25, TF-IDF, and Hybrid Search for MCP Tool Discovery
Benchmarking BM25, TF-IDF, and hybrid search for MCP tool discovery across 916 tools. The 80/20 TF-IDF/BM25 hybrid hits 21% Top-1 accuracy in under 1ms.
10 min
Indirect Prompt Injection Defense for MCP Tools: A Technical Guide
MCP tools that read emails, CRM records, and tickets are indirect prompt injection vectors. Here's how we built a two-tier defense that scans tool results in ~11ms.
12 min
MCP vs A2A: Architecture, Security, and When to Use Each
MCP vs A2A: what each protocol standardizes, how they differ, their shared security risks including indirect prompt injection, and when to use one, both, or a hybrid architecture.
12 min
MCP vs API: What 200+ Connector Builds Taught Us
MCP wraps APIs, it doesn't replace them. After building 200+ connectors that serve both, here's when each approach wins.
14 min read
Justworks MCP Server FAQ
Does StackOne have a Justworks MCP server?
Justworks MCP server vs direct API integration — what's the difference?
How does Justworks authentication work for AI agents?
origin_owner_id.Are Justworks MCP tools vulnerable to prompt injection?
What is the context bloat of a Justworks agent and how do I avoid it?
Can I limit which actions my Justworks agent can access?
Can I create custom agent actions for my Justworks MCP server?
When should I NOT use a Justworks MCP server?
What AI frameworks and AI clients does the StackOne Justworks MCP server support?
Put your AI agents to work
All the tools you need to build and scale AI agent integrations, with best-in-class connectivity, execution, and security.