[Vaishali123t]

Unwrap DAB’s { "value": [...] } response in built-in and custom MCP tools, and add regression tests for both paths.

Why make this change?

• Fixes Double value in MCP response #3848 — MCP stored-procedure responses contain a duplicate value wrapper, making returned rows harder to consume.
• The SQL engine’s SqlResponseHelpers.OkResponse() already wraps result rows in { "value": [...] }. Both MCP adapters then placed that complete engine response inside their own value field, producing the nested shape shown in the issue.

What is this change?

• Unwrap the engine’s outer response envelope in both affected paths: built-in execute_entity and dynamic custom MCP tools. Preserve the rows themselves—including any legitimate array-valued column named value.
• Before, for one returned row:
  {
  "entity": "GetBook",
  "value": {
  "value": [{ "id": 1 }]
  },
  "status": "success"
  }

After:
{
"entity": "GetBook",
"value": [{ "id": 1 }],
"status": "success"
}

• Regression tests for both tools use SqlResponseHelpers.OkResponse() and verify empty results, multiple rows, and a row with an array-valued value column remain unchanged after unwrapping the outer envelope.

How was this tested?

• Integration Tests
• Unit Tests

Build

powershell
dotnet build src\Azure.DataApiBuilder.Mcp\Azure.DataApiBuilder.Mcp.csproj --no-restore --verbosity quiet

Result: passed with zero warnings and zero errors.

Focused unit tests

powershell
dotnet test src\Service.Tests\Azure.DataApiBuilder.Service.Tests.csproj --no-build --no-restore --filter "FullyQualifiedNameAzure.DataApiBuilder.Service.Tests.Mcp.ExecuteEntityToolTests|FullyQualifiedNameAzure.DataApiBuilder.Service.Tests.Mcp.DynamicCustomToolTests" --verbosity quiet

Result: 106 passed, 0 failed, 0 skipped.

The six new regression cases were also run against the original adapter
implementation: all six failed before the fix and passed with the fix.
They verify empty results, multiple rows, and preservation of a legitimate
array-valued column named value through both tools.

SQL-backed integration tests

The following classes were run separately against an isolated local
SQL Server 2022 database:

powershell
dotnet test src\Service.Tests\Azure.DataApiBuilder.Service.Tests.csproj --no-build --no-restore --filter "FullyQualifiedName~ExecuteEntityToolMsSqlIntegrationTests" --verbosity quiet

dotnet test src\Service.Tests\Azure.DataApiBuilder.Service.Tests.csproj --no-build --no-restore --filter "FullyQualifiedName~DynamicCustomToolMsSqlIntegrationTests" --verbosity quiet

Results: 8/8 built-in-tool tests and 16/16 custom-tool tests passed.

Environment qualification: the unmodified shared fixture requires newer
SQL vector/native JSON types unavailable on this local SQL Server 2022
instance. A reviewer-only setup configured the isolated database and used
nvarchar(max) for those unrelated fixture columns. The stored procedures,
PR implementation, and PR test assertions were unchanged. These results
are not an unmodified full-suite or CI pass.

Additional reviewer-only HTTP validation

Seven additional checks passed through DAB's in-process HTTP test server
against the real SQL database:

• execute_entity: single-row, empty and multirow results.
• Dynamic custom tools: single-row, empty and multirow results.
• REST stored-procedure response: retained its existing single value envelope.

These checks used a temporary review harness, not tests included in this PR.
No full cross-database suite or CI pass is claimed.

Sample Request(s)

Using the repository's MSSQL test configuration, after initializing an MCP
session, send these tools/call requests to /mcp with the negotiated
protocol version, session header, and appropriate authentication.

Built-in tool:

json
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "execute_entity",
"arguments": {
"entity": "GetBook",
"parameters": { "id": 1 }
}
}
}

Equivalent custom tool:

json
{
"jsonrpc": "2.0",
"id": 2,
"method": "tools/call",
"params": {
"name": "get_book",
"arguments": { "id": 1 }
}
}

For both tools, the decoded JSON inside MCP result.content[0].text
contains a single value array holding the actual book rows. The first
row has id: 1; the engine's additional value envelope is absent.
A nonexistent ID returns "value": [].

REST compatibility control:

http
GET /api/GetBook?id=1

The REST response retains its established {"value":[...]} envelope.
No CLI behavior changes are introduced.

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Vaishali123t]

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[Copilot]

🟢 Approval recommended

The focused fix covers both execution paths with regression tests and no blocking issues identified; tests were not executed.

No open issues 🎉

What changed in this PR

Fixes nested value envelopes in DAB’s built-in and custom MCP stored procedure responses.

Changes:

• Centralizes envelope unwrapping and array normalization.
• Applies the shared helper to both execution paths.
• Adds regression tests and tightens SQL Server integration assertions.

File	Description
src/​Service.Tests/​Mcp/​ExecuteEntityToolTests.cs	Tests built-in envelope unwrapping.
src/​Service.Tests/​Mcp/​ExecuteEntityToolMsSqlIntegrationTests.cs	Requires a direct result array.
src/​Service.Tests/​Mcp/​DynamicCustomToolTests.cs	Tests custom-tool envelope unwrapping.
src/​Service.Tests/​Mcp/​DynamicCustomToolMsSqlIntegrationTests.cs	Requires a direct result array.
src/​Azure.DataApiBuilder.Mcp/​Utils/​McpResponseBuilder.cs	Adds shared result normalization.
src/​Azure.DataApiBuilder.Mcp/​Core/​DynamicCustomTool.cs	Uses shared normalization.
src/​Azure.DataApiBuilder.Mcp/​BuiltInTools/​ExecuteEntityTool.cs	Uses shared normalization.

_{Review effort: Balanced}

[Vaishali123t]

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