[Copilot]

Why make this change?

Generated OpenAPI documents omitted info.description even when runtime.mcp.description was configured. The document should use the top-level description, including when multiple configuration files are combined.

What is this change?

• Set OpenApiInfo.Description from the resolved runtime MCP description in BuildOpenApiDocument.
• Add unit coverage for the serialized OpenAPI description.

How was this tested?

• Integration Tests
• Unit Tests

Sample Request(s)

Configure the server description:

{
  "runtime": {
    "mcp": {
      "description": "This server provides access to the company database."
    }
  }
}

The generated OpenAPI document includes:

{
  "info": {
    "description": "This server provides access to the company database."
  }
}

• Fixes [Enh]: The info.description field in the OpenAPI output is never populated. #3702

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[Copilot]

🟢 Approval recommended

There are no active review issues for the change that populates the OpenAPI description from the runtime MCP description.

No open issues 🎉

What changed in this PR

Populates OpenAPI info.description from the existing runtime MCP description, giving DAB a shared server description without adding a separate configuration setting.

Changes:

• Sets OpenApiInfo.Description from the resolved runtime configuration.
• Adds a unit test verifying that the description appears in serialized OpenAPI output.

File	Description
src/​Service.Tests/​UnitTests/​OpenApiDocumentorUnitTests.cs	Adds description serialization coverage and updates test helpers to accept an MCP description.
src/​Core/​Services/​OpenAPI/​OpenApiDocumentor.cs	Maps the runtime MCP description to OpenAPI document metadata.

_{Review effort: Balanced}