Invalid input: expected record, received array

### Server

observability-mcp

### What did you do?

When using `@google-cloud/observability-mcp@latest` with Gemini CLI, certain tool calls (e.g. `list_metric_descriptors`, `list_log_entries`, etc.) are giving below error

{
"error": "MCP tool 'list_metric_descriptors' reported tool error for function call: {\"name\":\"list_metric_descriptors\",\"args\":{\"name\":\"projects/project-xyz\"}}
with response: [{\"functionResponse\":{\"name\":\"list_metric_descriptors\",\"response\":{\"error\":{\"message\":\"[\\n {\\n \\\"expected\\\": \\\"record\\\",\\n
\\\"code\\\": \\\"invalid_type\\\",\\n \\\"path\\\": [\\n \\\"structuredContent\\\"\\n ],\\n \\\"message\\\": \\\"Invalid input: expected record, received
array\\\"\\n }\\n]\",\"isError\":true}}}}]"
}

### What did you see happen?

{
"error": "MCP tool 'list_metric_descriptors' reported tool error for function call: {\"name\":\"list_metric_descriptors\",\"args\":{\"name\":\"projects/project-xyz\"}}
with response: [{\"functionResponse\":{\"name\":\"list_metric_descriptors\",\"response\":{\"error\":{\"message\":\"[\\n {\\n \\\"expected\\\": \\\"record\\\",\\n
\\\"code\\\": \\\"invalid_type\\\",\\n \\\"path\\\": [\\n \\\"structuredContent\\\"\\n ],\\n \\\"message\\\": \\\"Invalid input: expected record, received
array\\\"\\n }\\n]\",\"isError\":true}}}}]"
}

### What did you expect to see?

It should be able to accept the returned content in the given format

Reproduce the issue with observability-mcp using Gemini CLI and the list_metric_descriptors or list_log_entries tool calls shown in the report. Trace how the returned structuredContent is shaped, then verify that the documented array response is accepted without the invalid-type error.

Written by the indexing model from the issue text.