FLOW-1577: Fix double JSON.parse error in MCP tool return message parsing - (Jira Coding Agent)

[ccallcottstevens]

Fix JSON parsing error for MCP tool returns caused by double-stringified payloads

This PR addresses a SyntaxError occurring when parsing MCP tool return messages due to the backend accidentally double-stringifying the JSON payload in toolCallMessage.args. The fix adds defensive parsing logic to detect and correctly parse double-stringified JSON, ensuring the UI displays meaningful tool invocation labels instead of generic fallbacks.

Key changes:

• Enhance safeJsonParse utility to detect and parse double-stringified JSON strings.
• Update parseToolReturnMessage to use the improved parsing for MCP tool return messages (mcp__atlassian__invoke_tool, mcp__atlassian__get_tool_schema, mcp__scout__invoke_tool).
• Add comprehensive tests covering scenarios with double-stringified MCP tool arguments to prevent regressions.

Impact:

• Prevents silent degradation where users see generic fallback text instead of specific MCP tool invocation details.
• Improves user experience by showing accurate tool invocation messages in the chat UI.
• Maintains existing error handling without crashing or blocking user interaction.

This is a defensive, low-risk fix that mitigates a medium-severity issue affecting MCP tool integrations. Further backend investigation and UX improvements are recommended as next steps.

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[atlassian]

The issue is ready for review, and the acceptance criteria have been met:

• ✅ Implement defensive JSON parsing to handle double-stringified MCP tool args in parseToolReturnMessage, so the UI displays meaningful tool invocation labels instead of generic fallbacks.
• ✅ Add test coverage for double-stringified JSON scenarios to prevent regressions.
• ✅ Maintain existing error handling without crashing or blocking user interaction.

Check Jira issue