PyAirbyte MCP sync_source_to_cache Tool Bug Report

Summary

The PyAirbyte MCP sync_source_to_cache tool consistently fails with AirbyteConnectorConfigurationMissingError when attempting to sync data from a declarative connector, even when providing valid configuration parameters.

Environment

• PyAirbyte MCP v0.31.4 (Python v3.10.16)
• FastMCP version: 2.12.3
• MCP SDK version: 1.15.0

Bug Description

The sync_source_to_cache tool fails during configuration validation at line 603 in /airbyte/mcp/_local_ops.py when calling source.set_config(). The error occurs regardless of how the config parameter is provided:

1. Empty object: "config": {}
2. Null value: "config": null
3. Omitted parameter (relying on default)

Error Details

AirbyteConnectorConfigurationMissingError: Connector is missing configuration.
    Provide via `set_config()`
    Connector Name: 'source-rick-and-morty-api'

Stack Trace:

/airbyte/mcp/_local_ops.py:603 in sync_source_to_cache
source.set_config()
↓
/airbyte/sources/base.py:295 in set_config
self.validate_config()
↓
/airbyte/_connector_base.py:176 in validate_config
config = hydrate_config_from_secret_manager()
↓
/airbyte/_connector_base.py:152 in _hydrated_config
return hydrate_config_from_secret_manager()
↓
/airbyte/_connector_base.py:139 in get_config
raise exc.AirbyteConnectorConfigurationMissingError()

Reproduction Steps

1. Create a valid declarative connector manifest (Rick and Morty API example)
2. Call sync_source_to_cache with parameters:

   {
     "source_connector_name": "source-rick-and-morty-api",
     "config": {},
     "streams": ["characters"],
     "manifest_path": "/path/to/rick_and_morty_manifest.yaml"
   }

3. Tool fails with configuration missing error

Expected Behavior

The tool should successfully sync data from the declarative connector using the provided manifest file, especially when the connector requires no authentication (empty config spec).

Actual Behavior

Tool fails with AirbyteConnectorConfigurationMissingError during config validation, preventing any data sync operations.

Connector Manifest Details

The test connector has an empty connection specification:

spec:
  type: Spec
  connection_specification:
    type: object
    $schema: http://json-schema.org/draft-07/schema#
    required: []
    properties: {}
    additionalProperties: true

Impact

This bug blocks the complete PyAirbyte MCP testing pipeline, preventing:

• Local data synchronization testing
• SQL query testing on cached data
• End-to-end connector validation workflows

Additional Context

• The Connector Builder MCP tools work correctly for manifest validation and stream testing
• The issue appears to be specific to the PyAirbyte MCP configuration handling
• This was discovered during comprehensive MCP server testing

Logs

PyAirbyte logs written to: /tmp/airbyte/logs/2025-09-26/airbyte-log-*.log
Connector logs written to: /tmp/airbyte/logs/source-rick-and-morty-api/source-rick-and-morty-api-log-*.log