Fix deserialization of URL

[jackadamson]

Description

Fixes #163 by passing around a string URL to child functions, while still using AnyUrl for doing validation.

Server Details

• Server: fetch
• Changes to: tools

Motivation and Context

Minor bug fix to address #163

How Has This Been Tested?

I was able to reproduce the issue locally, and after this change it works in both the npx inspector and in the Claude Desktop app.

Breaking Changes

No breaking chanes.

Types of changes

• New MCP Server
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My server 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

[dsp-ant]

Thank you