APIWeaver + fast-agent: Complete MCP Integration

APIWeaver is a MCP server that An MCP server that dynamically creates MCP servers from web API configurations. This allows you to easily integrate any REST API, GraphQL endpoint, or web service into an MCP-compatible tool that can be used by AI assistants like Claude..

When integrated with fast-agent, you can:

• Register and configure APIs at runtime without server restart
• Support for REST APIs, GraphQL endpoints, and web services
• Multiple authentication methods for different API requirements

This guide provides step-by-step instructions to set up APIWeaver in fast-agent, including configuration, examples, and troubleshooting.

What You'll Achieve

After completing this setup:

• APIWeaver will be fully integrated and operational
• You can use APIWeaver tools directly in fast-agent
• All APIWeaver capabilities will be available for your workflows
• Access to 6 different tools

Prerequisites

Before starting, ensure you have:

• fast-agent installed and configured
• Compatible operating system (Node.js, Cross-platform, Edge Environments)

Installation

Step 1: Install APIWeaver

Configuration

Step 2: Configure fast-agent

1. Open fast-agent settings
2. Navigate to MCP server configuration
3. Add APIWeaver server with appropriate settings
4. Save and restart if needed

Examples

Once configured, you can use APIWeaver in fast-agent:

Register REST API with Authentication

Add a REST API with Bearer token authentication

Ask fast-agent: "Register the JSONPlaceholder API (https://jsonplaceholder.typicode.com) with GET and POST methods"

Expected Result: API registered successfully with auto-generated tools for posts, users, and comments endpoints

GraphQL Endpoint Integration

Connect to a GraphQL API for data querying

Ask fast-agent: "Register the GitHub GraphQL API with authentication and create tools for repository queries"

Expected Result: GraphQL endpoint configured with query tools for repositories, issues, and user data

API Testing and Validation

Test API connectivity before integration

Ask fast-agent: "Test connection to the Stripe API with my API key before registering it"

Expected Result: Connection test successful with API schema validation and endpoint verification

Multi-API Workflow

Integrate multiple APIs for complex workflows

Ask fast-agent: "Register both Twitter API and SendGrid API to create a workflow for social media monitoring and email alerts"

Expected Result: Both APIs registered with tools for tweet monitoring, email sending, and automated workflow execution

Testing Your Setup

1. Launch fast-agent
2. Verify APIWeaver is available in the tools list
3. Test basic APIWeaver functionality

Troubleshooting

Common Issues

API Registration Failed

Symptoms: Registration errors, Invalid API configuration, Connection timeouts

Cause: Incorrect API URL, authentication issues, or network problems

Solution:

• Verify API endpoint URL is accessible
• Check authentication credentials are valid
• Test API manually with curl or Postman first
• Ensure network connectivity and firewall settings

Authentication Not Working

Symptoms: 401 Unauthorized, 403 Forbidden, Auth token invalid

Cause: Incorrect authentication method or invalid credentials

Solution:

• Verify authentication method matches API requirements
• Check API key/token is not expired
• Confirm header format and parameter names
• Test authentication with API documentation examples

Transport Mode Not Connecting

Symptoms: Connection refused, Transport errors, Client not recognizing server

Cause: Incorrect transport configuration or port conflicts

Solution:

• Use streamable-http for modern clients
• Check port is not in use: netstat -an | grep :8000
• Verify host/port settings match client configuration
• Try different transport modes (stdio/http/sse)

Python Dependencies Missing

Symptoms: Import errors, Module not found, Package installation failures

Cause: Missing Python packages or virtual environment issues

Solution:

• Install requirements: pip install -r requirements.txt
• Create virtual environment: python -m venv apiweaver-env
• Activate environment before installation
• Upgrade pip: python -m pip install --upgrade pip

API Schema Generation Failed

Symptoms: Tool generation errors, Schema parsing failures, Endpoint mapping issues

Cause: Unsupported API format or incomplete API documentation

Solution:

• Provide OpenAPI/Swagger specification if available
• Start with simple GET endpoints first
• Manually configure complex APIs step by step
• Check API documentation for required parameters

Poor Performance

Symptoms: Slow startup, High memory usage, Slow tool execution

Cause: Suboptimal configuration or resource constraints

Solution:

• Tune concurrency and pool size settings
• Optimize MCP server performance
• Check system resources and limits
• Profile application for bottlenecks

Agent Crashes Under Load

Symptoms: Out of memory errors, Process crashes

Cause: Resource limits exceeded

Solution:

• Reduce concurrency limits
• Increase memory limits if possible
• Implement graceful degradation
• Monitor resource usage patterns

MCP Server Timeouts

Symptoms: Tool execution timeouts, Connection errors

Cause: Server overload or network issues

Solution:

• Increase timeout values
• Implement retry logic
• Scale MCP server infrastructure
• Use connection pooling and caching

APIWeaver not appearing in fast-agent

Symptoms: Server not listed, Tools not available

Cause: Configuration or installation issue

Solution:

• Verify configuration syntax
• Check APIWeaver installation
• Restart fast-agent
• Check logs for error messages

Next Steps

Now that APIWeaver is integrated with fast-agent:

• Explore all APIWeaver capabilities through fast-agent
• Check out other MCP servers that work with fast-agent
• Join the MCP community for tips and support
• Consider contributing to APIWeaver development

Need Help?

• Search for APIWeaver documentation
• Check the fast-agent MCP guide
• Join the MCP community discussions