Improve error handling to use MCP tool-level errors

[wesleyjellis]

🤖 Generated with Claude Code

Problem

I noticed sometimes we return nil when something goes wrong, but there's a specific error response we can (and I think should) use

Solution

Checklist

• I have run this code, and it appears to resolve the stated issue.
• This PR has no user interface changes or has already received approval from product management to change the interface.
• Make a changie entry that explains the customer facing outcome of this change.

[Copilot]

Pull Request Overview

This PR improves error handling by wrapping native errors into MCP tool-level errors for consistent CLI responses.

• Updates newToolResult to return CallToolResult error objects instead of raw errors
• Replaces direct nil, err returns in Cobra commands with mcp.NewToolResultError or mcp.NewToolResultErrorFromErr
• Adds explicit parameter-required error messages for req.RequireString calls

Comments suppressed due to low confidence (2)

src/cmd/root.go:97

• [nitpick] The error message "operation failed" is very generic; consider adding context about which operation failed or using a more descriptive message.

return mcp.NewToolResultErrorFromErr("operation failed", err), nil

src/cmd/root.go:94

• Add unit tests for newToolResult to verify both success and error branches produce the expected CallToolResult instances with correct error wrapping.

func newToolResult(obj any, err error) (*mcp.CallToolResult, error) {

[derek-etherton-opslevel]

makes sense to me, thanks for the QoL improvements