Fix issue with calling tool, and add test

[gsabran]

Summary

Fix issue with calling tool where decoding the input would lead to an endless loop.

Details

• Fix an issue with tool calling
• Add a test to cover it, and to start testing the server

Checklist before merging

• If this is a new feature or a bug fix, I have added tests.

[codecov]

Codecov Report

Attention: Patch coverage is 33.80282% with 47 lines in your changes missing coverage. Please review.

Project coverage is 65.65%. Comparing base (ca552ec) to head (d805ebe).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
MCPServer/Sources/MCPServer.swift	21.42%	22 Missing ⚠️
.../Sources/mcp_interfaces/Interface+extensions.swift	0.00%	10 Missing ⚠️
MCPClient/Sources/MCPClientInterface.swift	0.00%	6 Missing ⚠️
MCPInterface/Sources/Interfaces.swift	0.00%	5 Missing ⚠️
MCPClient/Sources/MCPClient.swift	25.00%	3 Missing ⚠️
MCPServer/Sources/MCPServerInterface.swift	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   56.46%   65.65%   +9.19%     
==========================================
  Files          26       26              
  Lines        1571     1520      -51     
==========================================
+ Hits          887      998     +111     
+ Misses        684      522     -162     

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