A known method whose params do not deserialize is answered with -32601 Method not found
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評估
- 難度
- 4/5
- 預估耗時
- 3-5 天
- 新手友好度
- 35/100
- Issue 類型
- 缺陷
- 描述清晰度
- 基本清楚
- 活躍度
- 活躍
- 技術堆疊
- rust
研究方向
Start by reading the ClientRequest untagged enum and the default on_custom_request handler described in the issue; compare how typed request deserialization failures reach that handler with how unknown methods are handled. Check the existing request error tests and add cases for the malformed tools/call, prompts/get, and resources/read params. Done means known methods with invalid params return -32602, while an unknown method still returns -32601.
由索引模型根據 Issue 內容生成。
描述
Describe the bug
When a request names a standard method but its params do not fit that method's type, the server answers -32601 with the method name as the message. The client is told the server has no tools/call, when the problem is in its own arguments.
To Reproduce (main at 808124b, also 3.5.1; stdio, after a 2025-11-25 handshake, server built with #[tool_router] / #[prompt_router])
| request | response |
|---|---|
tools/call, no params |
-32601 tools/call |
tools/call, params: {} |
-32601 tools/call |
tools/call, params: {"name": 7, "arguments": {}} |
-32601 tools/call |
tools/call, params: {"name": "ok", "arguments": "x"} |
-32601 tools/call |
prompts/get, params: {"name": 7} |
-32601 prompts/get |
resources/read, params: {"uri": 7} |
-32601 resources/read |
fixture/unknown (control) |
-32601 fixture/unknown |
On 2026-07-28 the rows that carry params behave the same; the row without params is correctly answered with -32602 for the missing _meta.
Why
ClientRequest is #[serde(untagged)]. When the typed variant for the method fails, the message falls through to CustomRequest, and the default on_custom_request returns METHOD_NOT_FOUND. Same shape as #1345, one level down.
Expected behavior
-32602 Invalid params when the method is one the SDK defines and its params do not deserialize. The tools page lists "Malformed requests (requests that fail to satisfy CallToolRequest schema)" under protocol errors, and the Go, Python and TypeScript 2.x SDKs answer these requests with -32602.
Related, smaller
A request whose params is not an object ("params": []) is answered with {"jsonrpc":"2.0","error":{"code":-32600,"message":"Invalid request"}}. The response has no id member, although the request's id was readable, so the sender cannot match it. I can split this into its own issue if you prefer.
I can send a PR for the first part.
AI disclosure: investigated and drafted with Claude Code; I reviewed it.
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