panic in pods_log when "previous" argument is non-bool type (string)

[jgericke]

Summary

The pods_log tool panics if the previous argument is passed as a non-boolean JSON type (for example, string "false"). In such cases, the interface conversion previous.(bool) fails and causes a runtime panic.

Steps to reproduce

1. Deploy kubernetes-mcp-server with LlamaStack or an agent sending a pods_log tool call where previous is a string (e.g. "previous": "false").
2. Observe the server log panics with something like:
   panic: interface conversion: interface {} is string, not bool

(From a LlamaStack call to pods_log, where previous is erroneously set to string)

INFO     2025-09-26 03:55:14,704 llama_stack.providers.inline.agents.meta_reference.agent_instance:890 agents: executing tool call: pods_log with     
         args: {'container': '', 'name': 'failing-test-pod', 'namespace': 'aiops-test', 'previous': 'false', 'tail': '100'}                           
03:55:14.705 [START] tool_execution
ERROR    2025-09-26 03:55:15,608 mcp.client.sse:109 uncategorized: Error in sse_reader

Resulting panic in kubernetes-mcp-server

I0926 03:55:15.596574       1 mcp.go:215] "mcp tool call: pods_log(map[container: name:failing-test-pod namespace:aiops-test previous:false session_id:6e911834-2541-4db1-beff-91c78efa3134 tail:100])"
...
panic: interface conversion: interface {} is string, not bool

goroutine 150 [running]:
github.com/containers/kubernetes-mcp-server/pkg/toolsets/core.podsLog({{0x2a67728, 0xc000b089f0}, 0xc000596088, {0x2a3f440, 0xc0003c0780}, {0x2a52240, 0x3f2ed40}})
        /Users/runner/work/kubernetes-mcp-server/kubernetes-mcp-server/pkg/toolsets/core/pods.go:403 +0x608
github.com/containers/kubernetes-mcp-server/pkg/mcp.ServerToolToM3LabsServerTool.func1({0x2a67728, 0xc000b089f0}, {{{0xc0008e86a0, 0xa}, {0x0}}, 0xc0007ffaa0, {{0xc0008e86b0, 0x8}, {0x2203960, 0xc000b08a80}, ...}})
        /Users/runner/work/kubernetes-mcp-server/kubernetes-mcp-server/pkg/mcp/m3labs.go:46 +0x127
github.com/containers/kubernetes-mcp-server/pkg/mcp.toolCallLoggingMiddleware.func1({0x2a67728, 0xc000b089f0}, {{{0xc0008e86a0, 0xa}, {0x0}}, 0xc0007ffaa0, {{0xc0008e86b0, 0x8}, {0x2203960, 0xc000b08a80}, ...}})
        /Users/runner/work/kubernetes-mcp-server/kubernetes-mcp-server/pkg/mcp/mcp.go:222 +0x35f
github.com/mark3labs/mcp-go/server.(*MCPServer).handleToolCall(0xc00022e960, {0x2a67728, 0xc000b089f0}, {0x204a3a0, 0xc0008e8680}, {{{0xc0008e86a0, 0xa}, {0x0}}, 0xc0007ffaa0, {{0xc0008e86b0, ...}, ...}})
        /Users/runner/go/pkg/mod/github.com/mark3labs/mcp-go@v0.40.0/server/server.go:1187 +0x3e6
github.com/mark3labs/mcp-go/server.(*MCPServer).HandleMessage(0xc00022e960, {0x2a67760?, 0xc00036cd70?}, {0xc0009480f0, 0xef, 0xf0})
        /Users/runner/go/pkg/mod/github.com/mark3labs/mcp-go@v0.40.0/server/request_handler.go:324 +0xc28
github.com/mark3labs/mcp-go/server.(*SSEServer).handleMessage.func1({0x2a67760?, 0xc00036cd70?})
        /Users/runner/go/pkg/mod/github.com/mark3labs/mcp-go@v0.40.0/server/sse.go:528 +0x89
created by github.com/mark3labs/mcp-go/server.(*SSEServer).handleMessage in goroutine 148
        /Users/runner/go/pkg/mod/github.com/mark3labs/mcp-go@v0.40.0/server/sse.go:524 +0x485

Root cause

In pods.go (or equivalent), the handler code does something like:

previous := params.GetArguments()["previous"]
if previous != nil {
    previousBool = previous.(bool)
}

Proposed fix

Change the handling to safely coerce/convert previous from known types to bool, defaulting to false otherwise in the podLogs function - I've tested locally and it mitigates the issue:

	previous := params.GetArguments()["previous"]
	var previousBool bool
	if previous != nil {
		// Convert to bool - safely handle both bool, string, float64, int types
		switch v := previous.(type) {
		case bool:
			previousBool = v
		case string:
			previousBool = v == "true" || v == "True" || v == "TRUE" || v == "1"
		case float64:
			previousBool = v != 0
		case int:
			previousBool = v != 0
		default:
			// Default to false for unknown types
			previousBool = false
		}
	}

Is this acceptable? I’ll prepare a PR once the issue is accepted.

[manusa]

The jsonschema precisely describes the input as boolean.

I'm not sure we should support parsing for multiple input types (such as string or numbers).
By following this approach, will make more challenging the migration to go-sdk since we'll eventually move to structured inputs and maybe even be able to infer the jsonschemas from these.

IMO we should do the type check just like we're doing in and not support other kinds of inputs:

kubernetes-mcp-server/pkg/toolsets/core/pods.go

Lines 332 to 334 in 053fb2e

	if v, ok := params.GetArguments()["all_namespaces"].(bool); ok {
	podsTopOptions.AllNamespaces = v
	}

We missed this in the PR review when the previous feature was implemented in #256