mcp__claude_ai_Atlassian__createJiraIssue always invoked with empty parameters after ToolSearch load (deferred tool regression)

Description

When loading mcp__claude_ai_Atlassian__createJiraIssue via ToolSearch and invoking it, the tool is always called with zero parameters — all fields arrive as undefined. This causes an immediate validation error on every attempt. Read tools on the same MCP server (e.g. getJiraIssue) work correctly.

Claude Code Version

2.1.170 (Claude Code)

Model

claude-sonnet-4-6

Repro Steps

1. Open a project with the claude.ai Atlassian MCP connected
2. Confirm mcp__claude_ai_Atlassian__createJiraIssue appears in the deferred tools list in the system prompt
3. Load its schema via ToolSearch: select:mcp__claude_ai_Atlassian__createJiraIssue
4. Invoke mcp__claude_ai_Atlassian__createJiraIssue with required fields (cloudId, projectKey, issueTypeName, summary)

Expected

Tool is called with the provided parameters.

Actual

Tool is called with zero parameters — all fields arrive as undefined.

Error:

MCP error -32602: Input validation error: Invalid arguments for tool createJiraIssue:
  cloudId: Required (received undefined)
  projectKey: Required (received undefined)
  issueTypeName: Required (received undefined)
  summary: Required (received undefined)

Hypothesis / Root Cause

This worked as recently as June 19, 2026. The key difference between then and now appears to be that createJiraIssue and other Atlassian write tools are now listed as deferred tools in the system prompt (requiring ToolSearch to load their schemas), whereas previously their schemas appeared to be pre-loaded.

Hypothesis: a bug exists in the deferred tool invocation path specifically for write operations — the schema loads successfully via ToolSearch, but the subsequent invocation generates with an empty parameter block. Read tools on the same server (getJiraIssue) are unaffected, possibly because they were always deferred or the bug is specific to the write-tool invocation path.

Additional Context

• Reproducible across fresh conversations (not a session context/compression issue)
• mcp__claude_ai_Atlassian__getJiraIssue works correctly with parameters
• mcp__claude_ai_Atlassian__createIssueLink has the same empty-parameter failure
• ToolSearch returns the schema successfully before each failed invocation