Bug Description
The MCPSearch tool is generating tool_reference objects with tool_name values exceeding the 64-character API limit.
Environment Info
- Platform: darwin
- Terminal: iTerm.app
- Version: 2.1.6
- Feedback ID: a666cb3b-fbf0-4ce0-b036-eeef93ee1d08
Errors
[{"error":"Error: LSP server plugin:typescript-lsp:typescript failed to start: Executable not found in $PATH: \"typescript-language-server\"\n at start (/$bunfs/root/claude:2266:22300)\n at async $ (/$bunfs/root/claude:2266:24752)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: LSP server plugin:pyright-lsp:pyright failed to start: Executable not found in $PATH: \"pyright-langserver\"\n at start (/$bunfs/root/claude:2266:22300)\n at async $ (/$bunfs/root/claude:2266:24752)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Executable not found in $PATH: \"typescript-language-server\"\n at spawn (unknown)\n at spawn (node:child_process:667:35)\n at spawn (node:child_process:14:39)\n at start (/$bunfs/root/claude:2266:20845)\n at start (/$bunfs/root/claude:2266:22354)\n at $ (/$bunfs/root/claude:2266:24752)\n at $ (/$bunfs/root/claude:2266:25727)\n at _ (/$bunfs/root/claude:2266:32514)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Executable not found in $PATH: \"pyright-langserver\"\n at spawn (unknown)\n at spawn (node:child_process:667:35)\n at spawn (node:child_process:14:39)\n at start (/$bunfs/root/claude:2266:20845)\n at start (/$bunfs/root/claude:2266:22354)\n at $ (/$bunfs/root/claude:2266:24752)\n at $ (/$bunfs/root/claude:2266:25727)\n at _ (/$bunfs/root/claude:2266:32514)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Failed to start LSP server plugin:typescript-lsp:typescript: Executable not found in $PATH: \"typescript-language-server\"\n at <anonymous> (/$bunfs/root/claude:2266:32536)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Failed to start LSP server plugin:pyright-lsp:pyright: Executable not found in $PATH: \"pyright-langserver\"\n at <anonymous> (/$bunfs/root/claude:2266:32536)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"}]Notes
I don't believe the errors above are relevant. Below, however, I have attached Claude's own analysis of, well, itself:
Problem Identified:
The MCPSearch tool is generating tool_reference objects with tool_name values exceeding the 64-character API limit.
Root Cause:
Several MCP tool names in the available tool list exceed this limit:
- mcp__awslabs_cloudwatch-mcp-server__get_recommended_metric_alarms (66 characters)
- Similar long names in the workspace-mcp and cloudwatch-mcp-server collections
Error Location:
The error occurs in messages.6.content.0.tool_result.content.1.tool_reference.tool_name, indicating the MCPSearch tool is returning
references to these tools in its results, which then fail API validation when the tool result is submitted.
Assessment:
This is a system-level constraint violation. The MCPSearch tool implementation needs to either:
- Truncate or abbreviate tool names in tool_reference objects to fit within 64 characters
- Use alternative reference mechanisms for tools with long names
- Filter out tools with names exceeding the limit from search results
Recommendation:
This issue should be reported to the Claude Code development team. The MCPSearch tool's output formatting is incompatible with the
API's tool_reference constraints.
Unable to resolve this issue from the conversation level. This requires modification to the MCPSearch tool implementation itself.
Bug Description
The MCPSearch tool is generating tool_reference objects with tool_name values exceeding the 64-character API limit.
Environment Info
Errors
[{"error":"Error: LSP server plugin:typescript-lsp:typescript failed to start: Executable not found in $PATH: \"typescript-language-server\"\n at start (/$bunfs/root/claude:2266:22300)\n at async $ (/$bunfs/root/claude:2266:24752)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: LSP server plugin:pyright-lsp:pyright failed to start: Executable not found in $PATH: \"pyright-langserver\"\n at start (/$bunfs/root/claude:2266:22300)\n at async $ (/$bunfs/root/claude:2266:24752)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Executable not found in $PATH: \"typescript-language-server\"\n at spawn (unknown)\n at spawn (node:child_process:667:35)\n at spawn (node:child_process:14:39)\n at start (/$bunfs/root/claude:2266:20845)\n at start (/$bunfs/root/claude:2266:22354)\n at $ (/$bunfs/root/claude:2266:24752)\n at $ (/$bunfs/root/claude:2266:25727)\n at _ (/$bunfs/root/claude:2266:32514)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Executable not found in $PATH: \"pyright-langserver\"\n at spawn (unknown)\n at spawn (node:child_process:667:35)\n at spawn (node:child_process:14:39)\n at start (/$bunfs/root/claude:2266:20845)\n at start (/$bunfs/root/claude:2266:22354)\n at $ (/$bunfs/root/claude:2266:24752)\n at $ (/$bunfs/root/claude:2266:25727)\n at _ (/$bunfs/root/claude:2266:32514)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Failed to start LSP server plugin:typescript-lsp:typescript: Executable not found in $PATH: \"typescript-language-server\"\n at <anonymous> (/$bunfs/root/claude:2266:32536)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"},{"error":"Error: Failed to start LSP server plugin:pyright-lsp:pyright: Executable not found in $PATH: \"pyright-langserver\"\n at <anonymous> (/$bunfs/root/claude:2266:32536)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-01-13T21:52:02.955Z"}]Notes
I don't believe the errors above are relevant. Below, however, I have attached Claude's own analysis of, well, itself:
Problem Identified:
The MCPSearch tool is generating tool_reference objects with tool_name values exceeding the 64-character API limit.
Root Cause:
Several MCP tool names in the available tool list exceed this limit:
Error Location:
The error occurs in messages.6.content.0.tool_result.content.1.tool_reference.tool_name, indicating the MCPSearch tool is returning
references to these tools in its results, which then fail API validation when the tool result is submitted.
Assessment:
This is a system-level constraint violation. The MCPSearch tool implementation needs to either:
Recommendation:
This issue should be reported to the Claude Code development team. The MCPSearch tool's output formatting is incompatible with the
API's tool_reference constraints.
Unable to resolve this issue from the conversation level. This requires modification to the MCPSearch tool implementation itself.