[BUG] Duplicate tools when using an "sdk" McpServer
Preflight Checklist
- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code
What's Wrong?
When passing an MCP server of type "sdk" into the TS SDK, on the second message of a multiturn chat, I am getting the problem:
API Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"tools: Tool names must be unique.\"},\"request_id\":\"req_011CTA5VA5xFXK2mkaw27P2y\"}I added the oninitialize callback on my custom MCP server, and noticed that it is being initialized twice.
Not sure if this is a problem on how I've setup the server, or if there is a bug on the Claude Code side, but I am only creating the SDK server once and passing it into mcpServers once and I am getting this behavior.
The diff of our implementation is here, where we moved it from an HTTP server to an SDK one: https://github.com/zed-industries/claude-code-acp/pull/50/files#diff-8a5c4a5a3d949e31532fec3de206c63c156b3155181a27534871599db24c3899R149
What Should Happen?
I would expect when passing in an SDK MCP server it would only get initialized once, and the tools wouldn't get sent to the model more than once.
Error Messages/Logs
Steps to Reproduce
- Pass in an MCP server of type "sdk" in the config
- Send two subsequent messages to the SDK
Claude Model
None
Is this a regression?
I don't know
Last Working Version
_No response_
Claude Code Version
1.0.113
Platform
Anthropic API
Operating System
macOS
Terminal/Shell
Other
Additional Information
_No response_
6 Comments
Great catch, @benbrandt! Will be fixed in the next release.
@dltn I've seen a few new releases, but am still seeing the same behavior. I assume you'll update the ticket once this is fixed?
I'm having this issue constantly as well. I'm running it in a container trying to use the sdk tools.
@benbrandt hmm, should've been out in v1.0.118. You're still seeing issues on/after that version?
@dltn thanks it is working now! I saw 1.0.118, but it was only tagged as a
nextrelease so I wasn't sure if it was ready or not.but both it and v1.0.119 are working. Thanks!
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