Error: Insufficient error details from SDK error handling

[masda70]

Describe the bug
The SDK's error handling does not provide sufficient error details when encountering complex error types. Notably, when an AggregateError is thrown (e.g., from pg.Pool.connect()), users only see "MCP error -32603" without any underlying error information that could help diagnose the issue.

To Reproduce

1. Use any MCP server that may throw complex errors (e.g., @modelcontextprotocol/server-postgres with invalid connection)
2. Observe that error messages lack important details
3. Example: Database connection errors only show "MCP error -32603" instead of the actual connection error details stored in AggregateError.errors[]

Expected behavior
The error handling system should:

1. Deeply inspect error objects to extract meaningful information
2. Handle common error types appropriately (including but not limited to AggregateError)
3. Present error information in a way that helps users diagnose issues

Additional context

• The AggregateError case highlights a broader need for better error inspection
• Different error types may store their important details in different properties
• A more robust error inspection system would improve the debugging experience across all MCP servers
• This could be designed as a general error handling enhancement, with AggregateError support being one of the initial use cases

[shanggqm]

I met same error，I try harder to debug , but I don't know how to fix it。

-----> result: get-forecast 工具执行失败，失败原因：MCP error -32603: [ { "code": "invalid_type", "expected": "string", "received": "undefined", "path": [ "params", "name" ], "message": "Required" } ]

my code is :

// create client
const transport = new StdioClientTransport({
      command: serverConfig.command,
      args: serverConfig.args,
      env: serverConfig.env
    });

// Create client
const client = new Client({
  name: serverConfig.name,
  version: '0.0.1',
}, {
  capabilities: {},
});

await client.connect(transport)


// call tool
const params = {"latitude": 34.0522, "longitude": -118.2437}
const result = await mcpClient.client.callTool(params);

[pcarion]

The callTool, as described in the Zod schema here, takes as the first parameter the name of the tool you want to call. Check your server configuration to get the name of the tool.

The code should look like:

const result = await client.callTool("get-forecast", {"latitude": 34.0522, "longitude": -118.2437});

This is not the same issue as the one described by the OP, the exception you receive is a Zod error describing what is missing in the payload (see schema linked above): it expects a name property in the params object : this property would contain the name of the tool