enhancement: more friendly interface to get service error

[4t145]

1. remove unused get_info and set_info.
2. make it more clear when user get an error after called method on peer.

Motivation and Context

explained in #188, and also aims to solve #177

How Has This Been Tested?

Breaking Changes

Removed get_info and set_info. And explained in #188

Types of changes

• 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 Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context