[BUG] LSP tool failures are reported as success: no is_error on the result, telemetry tool_result success=true

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When an LSP tool call fails, the result is reported as a success everywhere except in its text. The tool returns Error performing <operation>: …, but:

• the tool_result block in the transcript has no is_error: true;
• the OpenTelemetry tool_result event has success="true" and no error field.

This happens for every kind of failure we see: the server rejecting a request, the server process exiting, a file sync failing (Failed to sync file open …: Cannot send notification to LSP server …). Over three days on our machines all 209 tool_result events for LSP had success="true", while 14 of the matching transcript results were Error performing …. Anything that counts tool failures from telemetry (or from is_error) never sees LSP failures, and the model gets an error with no error flag.

What Should Happen?

A failed LSP operation should be marked like any other failed tool call: is_error: true on the tool result, and success="false" with the error text in the telemetry tool_result event.

Error Messages/Logs

# transcript tool_result (is_error absent)
Error performing findReferences: Failed to sync file open /…/use-inquiries.ts: Cannot send notification to LSP server '…'

# OTel event for the same call
{"event.name":"tool_result","tool_name":"LSP","success":"true","duration_ms":"36","tool_result_size_bytes":"200"}

Steps to Reproduce

1. Configure any plugin LSP server whose process exits on a request (or returns a JSON-RPC error for it).
2. Ask Claude to run that LSP operation, e.g. findReferences on a file of that language.
3. The tool returns Error performing findReferences: ….
4. In the transcript the tool_result has no is_error; with CLAUDE_CODE_ENABLE_TELEMETRY=1 and logs exported, the tool_result event for LSP has success="true".

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Claude Code Version

2.1.284 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other