Update tool name prefix separator from colon to double underscore

[NightRare]

This is to fix [#228] Tool names with colons violate MCP naming pattern

What I did
Update tool name prefix separator from colon : to double underscore __

Related issue

This fixes #228

[isiahw1]

✅ Tested and Verified

I've built and tested this PR locally and can confirm it successfully fixes the tool naming issue.

Test Results

Before PR #263:

• Tool names used colon separator: github-official:search_repositories
• Violated MCP naming pattern: ^[a-zA-Z0-9_-]{1,64}$

After PR #263:

• Tool names use double underscore: github-official__search_repositories
• Complies with MCP naming pattern ✓

Testing Process

1. Cloned repo and checked out PR branch (commit 88c3b9f)
2. Built with make docker-mcp
3. Verified installation: docker mcp version shows commit hash
4. Tested with docker mcp gateway run --servers github-official
5. Captured tool list output showing proper double-underscore format

Example Output

"name":"github-official__add_comment_to_pending_review"
"name":"github-official__add_issue_comment"
"name":"github-official__create_pull_request"

All 40 GitHub tools now use the correct naming convention.

Recommendation

This is a simple, focused fix that resolves issue #228. The change is minimal (one line) and works as expected. Ready to merge. 🚀

[null-runner]

Hey @NightRare, thanks for this fix!

While testing the __ separator change, I discovered that there's an additional issue preventing tool-name-prefix from working correctly: the gateway forwards the prefixed tool name to the remote server instead of the original name.

For example, when a client calls chromedev__new_page, the gateway sends chromedev__new_page to the remote server, which only knows about new_page and returns "tool not found".

I've opened #278 with a complementary fix that passes the original tool name to the handler. Together with your separator change, this should make tool-name-prefix fully functional.

[NightRare]

Hey @NightRare, thanks for this fix!

While testing the __ separator change, I discovered that there's an additional issue preventing tool-name-prefix from working correctly: the gateway forwards the prefixed tool name to the remote server instead of the original name.

For example, when a client calls chromedev__new_page, the gateway sends chromedev__new_page to the remote server, which only knows about new_page and returns "tool not found".

I've opened #278 with a complementary fix that passes the original tool name to the handler. Together with your separator change, this should make tool-name-prefix fully functional.

Thank you for the PR. This is a very good catch! 🎉