Symptom
A tools/list request that omits jsonrpc gets no bytes back. The server has already answered initialize, then stays silent for that id.
Evidence what you'll see
- The request that gets no response is
{"id":99,"method":"tools/list","params":{}}. - A one-element batch is also dropped. The issue's batch uses ids
100and101and gets no response either. - SDK
@modelcontextprotocol/sdk1.29.0, checked with@modelcontextprotocol/server-everythingv2.0.0and@modelcontextprotocol/server-memoryv0.6.3.
Why it happens
Schema validation fails in processReadBuffer() and the error goes to onerror. Nothing writes a JSON-RPC error for that id, so a client waiting on the id never resolves.
Affected versions
@modelcontextprotocol/sdk 1.29.0. The issue names server packages v2.0.0 and v0.6.3 on stdio. It does not name an operating system or a Node version.
Fix steps
0 of 2 done
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How to check it worked
- Id
99returns a JSON-RPC object. The server does not stop after the initialize response.
If it still fails
- The issue says a batch array is dropped the same way, with no response for ids
100and101. The linked issue does not name an SDK release after1.29.0.
Sources and credit
Summarized in our own words from these public reports. Credit goes to their authors.
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