[Bug]: Claude Code is adding prefixes to tool names that make them exceed the API's character limit.

[chrisvanbuskirk]

Bug Description

Hi, I'm trying to use XcodeBuildMCP with Claude Code.

List the simulators
⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.48.custom.name: String should have
at most 64 characters"}}

Debug Output

ios_simulator_build_and_run_by_name_workspace (45 characters)
ios_simulator_build_and_run_by_name_project (43 characters)
get_simulator_app_path_by_name_workspace (40 characters)

Editor/Client

Claude Code v0.2.100

MCP Server Version

1.3.4

LLM

Claude 3.7

MCP Configuration

{
  "mcpServers": {
    "XcodeBuildMCP": {
      "command": "mise",
      "args": [
        "x",
        "npm:xcodebuildmcp@1.3.4",
        "--",
        "xcodebuildmcp"
      ]
    }
  }
}

Steps to Reproduce

1. Configure the server to run with claude code.
2. Start claude
3. Try out a command

Expected Behavior

List the simulators on request and other commands.

Actual Behavior

Reports an error for any command

Error Messages

> List the simulators
  ⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.48.custom.name: String should have
     at most 64 characters"}}

[chrisvanbuskirk]

I should have checked the closed issues. Looks like the same thing as #3

[chrisvanbuskirk]

Since this works perfectly on Claude Desktop I have opened a bug with Anthropic anthropics/claude-code#955

[cameroncooke]

Thanks you for raise it, hopefully they can fix it now there is a few reports of the same issue. Will close this one for now.

[chrisvanbuskirk]

Yeah, I think the bug lies with Claude Code. Even Bolt is working fine. Thank you for this work.

[cameroncooke]

Fixed in 1.3.7 🎉