Add USA Spending MCP server

[thsmale]

Description

It leverages the official source of government spending data USASPENDING.gov. Which enables one to track government spending over time, search government spending by agency, explore government spending to communities, and much more.

Server Details

This is a stateless streamable HTTP MCP server.

Motivation and Context

The motivation behind this is increasing government transparency. Currently, when you ask LLM's specific questions regarding government spending data it is unable to access much of this data or it is outdated.

How Has This Been Tested?

I have tested it using Claude desktop, Cursor, and a simple OpenAI agents MCP client that is available in the test directory.

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

Currently, no API key is required to interact with the USA Spending API. Hence, it is not required to provide one as an environment variable.