eBay Negotiation API Server for AI Agents - n8n Workflow

E-commerce Sellers & Businesses: Those using eBay and wanting to automate personalized discount offers to interested buyers.
AI/LLM Developers: Professionals needing a secure, standardized n8n workflow endpoint (MCP) to integrate external APIs into their AI agents.
n8n Automation Engineers: Users looking for advanced examples of using the n8n trigger and tool n8n node architecture for AI integrations.
Data Scientists: Teams requiring automated access to eBay listing data for buyer engagement analysis.

This advanced n8n workflow transforms the specialized eBay Negotiation API into a seamless Multi-Capability Provider (MCP) server. By utilizing the dedicated MCP n8n trigger, this workflow allows external AI agents (like those built on OpenAI or similar frameworks) to access high-value eBay functions programmatically. The core value of this n8n workflow lies in its ability to securely expose two key operations—Find Eligible Listings and Send Discount Offer—as defined tools. Instead of requiring the AI to construct complex API calls, it simply requests the use of a tool, and this n8n workflow handles the authentication and request construction. This is a crucial n8n templates example for achieving complex e-commerce automation tasks driven entirely by an intelligent AI agent, significantly boosting efficiency and sales potential. Every n8n node is configured for maximum compatibility and ease of use.

The entire process is initiated by the Negotiation MCP Server n8n trigger, which acts as the inbound endpoint for the AI agent. This specialized n8n trigger constantly monitors for requests from the LLM asking to use one of the available tools.

1. AI Invocation: An external AI agent determines that it needs to perform an eBay operation (e.g., finding buyers or sending an offer) and sends a structured function call request to the MCP n8n trigger URL.


2. Tool Routing: The n8n workflow routes the incoming request to the corresponding HTTP Request Tool n8n node.


3. Dynamic Parameterization: Both key operations, Find Eligible Listings and Send Discount Offer, are configured to pull necessary input parameters dynamically from the AI request using $fromAI() expressions. For example, parameters like X-EBAY-C-MARKETPLACE-ID, limit, and offset are extracted directly from the AI's intent.


4. API Execution: The selected n8n node executes the secure, authenticated request (using OAuth2/HTTP Header authentication) against the eBay Negotiation API.


5. Response Handling: The response from eBay is immediately captured by the n8n node tool and fed back directly to the Negotiation MCP Server n8n trigger. The n8n trigger then relays the structured JSON response back to the originating AI agent, maintaining the original API structure for seamless consumption by the LLM.

To deploy this useful n8n workflow and start using it as an AI tool server, follow these setup instructions:

1. Import the n8n Workflow: Import this provided JSON code into your running n8n instance using the 'New' > 'Import from JSON' option.


2. Configure Credentials: Set up your OAuth2 credentials for eBay, as both HTTP Request Tool n8n node components require secure authentication (using a generic credential type via HTTP Header Authentication).


3. Activate the n8n Trigger: Ensure the Negotiation MCP Server n8n trigger is active. Click the 'Activate Workflow' toggle in the top right corner.


4. Obtain MCP URL: After activation, copy the generated webhook URL from the Negotiation MCP Server n8n node (look for the 'Webhooks' section or the path /negotiation-mcp).


5. Connect to AI Agent: Use the copied MCP URL in your external AI agent configuration (e.g., in your LangChain or custom LLM integration platform) to register this n8n workflow as an available tool.

This n8n workflow relies on a few key n8n node types to provide its functionality as an AI tool server:

Negotiation MCP Server (MCP Trigger):
Function: This is the specialized n8n trigger node that initiates the workflow. It serves as the webhook endpoint (/negotiation-mcp) designed specifically to receive function call requests from an AI agent.
Key Configuration: Configured to expose the subsequent HTTP Request Tool n8n nodes as callable functions to the LLM.

Find Eligible Listings (HTTP Request Tool n8n node):
Function: Executes a GET request to the /findeligibleitems endpoint on eBay's API. This determines which listings have interested buyers.
Key Configuration: Uses $fromAI() expressions to dynamically accept parameters like limit, offset, and the required X-EBAY-C-MARKETPLACE-ID header directly from the AI agent's request.

Send Discount Offer (HTTP Request Tool n8n node):
Function: Executes a POST request to the /sendoffertointerestedbuyers endpoint, sending a seller-initiated discount offer to eligible buyers.
* Key Configuration: Requires OAuth2 authentication and dynamically receives the critical X-EBAY-C-MARKETPLACE-ID header via a $fromAI() expression.