Describe the bug

When using github-mcp-server with Claude Code 1.0.3, sending any prompt results in an API error due to tool names exceeding the 64 character limit imposed by the server. The error prevents any interaction with Claude when github-mcp-server is installed.

This might be fundamentally a Claude Code issue:
anthropics/claude-code#955

Affected version

v0.4.0

Steps to reproduce the behavior

1. Install github-mcp-server:go install github.com/github/github-mcp-server/cmd/github-mcp-server@v0.4.0
2. Add to Claude Code:claude mcp add github-mcp-server -s user -- github-mcp-server stdio
3. Start Claude:claude
4. Send any prompt:hi
5. See error

Expected vs actual behavior

Expected: Claude should respond normally to the prompt, with github-mcp-server tools available for use.

Actual: Claude returns an API error and cannot process any prompts:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.16.custom.name: String should have at most 64 characters"}}

Analysis

Upon investigation of the server response, the following tool names exceed the 64 character limit:

• mcp__github-mcp-server__add_pull_request_review_comment_to_pending_review (66 characters)
• mcp__github-mcp-server__manage_repository_notification_subscription (67 characters)

The error does not occur when github-mcp-server is not installed, confirming that the issue is related to the tool name length.

Logs

> hi  ⎿ API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools.16.custom.name: String     should have at most 64 characters"}}