[BUG] Cannot get any MCP tool calls working at all in Claude Code, despite them working in Claude Desktop

[SamFold]

Environment

• Platform (select one):
  • [ X] Anthropic API
  • AWS Bedrock
  • Google Vertex AI
  • Other:
• Claude CLI version: 0.2.39
• Operating System: Mac OS 15.3.1
• Terminal: iTerm2

Bug Description

I have tools for say Google Searches and Web Scraping which both work fine in Claude Desktop app.

I then added these tools to Claude Code using claude mcp add-from-claude-desktop.

I see those servers as connected when I run Claude Code. E.g. google-search "connected"

However, when I try and get claude code to run these tools I always get the same error no matter my prompt:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.11.custom.name: String should match pattern '^[a-zA-Z0-9_-]{1,64}$'"}}

Steps to Reproduce

1. Add a tool to local Claude desktop app. E.g. https://github.com/adenot/mcp-google-search
2. Confirm tool works in Claude desktop
3. Add tool to Claude Code and try and make it work.

Expected Behavior

I expect Claude Code to run the Google Search

Actual Behavior

Claude Code produced the folowing error:
⎿  API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.11.custom.name: String should match pattern '^[a-zA-Z0-9_-]{1,64}$'"}}

Additional Context

No other context.

[ashwin-ant]

When you see them called in Claude Desktop, what are the tool names that you see? Can you include a screenshot?

[SamFold]

Ok, I worked this out. Claude Desktop supports a server name with spaces e.g. "sams Server". Claude Code will error if there is a space in the name.

Also, more importantly, if one server for Claude Code has an invalid name, ALL tool calls will fail with the above error:

⎿  API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.11.custom.name: String should match pattern '^[a-zA-Z0-9_-]{1,64}$'"}}

So if I have an MCP server called "sams Server", it will cause errors with another working server called "googleTools" for example.

Once I rename my server config "samsServer" and reimport it to Claude Code (after deleting it), all tools in Claude Code work.

[ashwin-ant]

This should be fixed now! Servers with spaces in the name no longer break.

[Yapppppppppppp]

Hi everyone,
I'm trying to understand how I can use MCP tools without needing Claude Desktop. Is it possible to use MCP with just a Claude API key? If so, could someone please guide me or share a general idea of how to set that up?

[pjgoodall]

no spaces in name. just plain broken

[github-actions]

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