[MCP] Prevent duplicating entities between custom tools and describe_entities #3076

souvikghosh04 · 2026-01-22T08:13:03Z

Why make this change?

Closes on - MCP-CustomTool: describe_entities filtering #3043

With custom tools, stored procedure entities could get listed in describe_entities even when they are configured as custom-tool-only (with dml-tools: false). This creates duplication since they already appear in tools/list. We need to filter stored procedures with dml-tools: false from describe_entities to avoid this duplication.

What is this change?

Added filtering logic to exclude stored procedure entities when dml-tools is explicitly set to false
The filtering ensures stored procedures are removed from describe_entities only when they are custom-tool-only (not available for DML operations)
Stored procedures with dml-tools: true (or null/default) continue to appear in describe_entities even if they have custom-tool: true, allowing dual exposure when needed

How was this tested?

Unit Tests
Manual Tests

Sample Request(s)

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "describe_entities"
  },
  "id": 1
}

…_entities

Copilot

Pull request overview

This PR prevents stored-procedure entities that are already exposed as dedicated custom MCP tools from being duplicated in the describe_entities response.

Changes:

Added filtering in DescribeEntitiesTool to skip stored procedures with entity.Mcp.CustomToolEnabled == true.
Added new MSTest coverage validating stored procedure filtering and ensuring tables/views remain unaffected.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs	Filters out custom-tool-enabled stored procedures from `describe_entities` results.
src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs	Adds tests verifying filtering behavior across stored procedures, tables/views, and `nameOnly` mode.

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src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

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src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

souvikghosh04 · 2026-01-22T09:49:02Z

/azp run

azure-pipelines · 2026-01-22T09:49:29Z

Azure Pipelines successfully started running 6 pipeline(s).

JerryNixon · 2026-01-22T17:42:33Z

Desired logic

	DML TOOLS = TRUE	DML TOOLS = FALSE
CUSTOM TOOL = TRUE	✔ describe_entities ✔ tools/list	✘ describe_entities ✔ tools/list
CUSTOM TOOL = FALSE	✔ describe_entities ✘ tools/list	✘ describe_entities ✘ tools/list

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

Aniruddh25

Waiting on what needs to be done for non stored proc entities

… Usr/sogh/describeentitiesfilter

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

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Copilot · 2026-01-31T05:15:10Z

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

+                        // Filter out entities when dml-tools is explicitly disabled (false).
+                        // This applies to all entity types (tables, views, stored procedures).
+                        // When dml-tools is false, the entity is not exposed via DML tools
+                        // (read_records, create_record, etc.) and should not appear in describe_entities.
+                        if (entity.Mcp?.DmlToolEnabled == false)
+                        {
+                            filteredDmlDisabledCount++;
+                            continue;
+                        }


The new filtering block excludes any entity with entity.Mcp?.DmlToolEnabled == false, regardless of entity type or CustomToolEnabled. This is broader than the PR description (stored-procedure, custom-tool-only de-duplication). If the intent is only to avoid duplication with custom tools, restrict the condition to stored procedures where CustomToolEnabled == true and DmlToolEnabled == false; otherwise, please update the PR description/tests to reflect the expanded behavior.

Copilot · 2026-01-31T05:15:11Z

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

+                        if (entity.Mcp?.DmlToolEnabled == false)
+                        {
+                            filteredDmlDisabledCount++;
+                            continue;
+                        }
+
                        if (!ShouldIncludeEntity(entityName, entityFilter))
                        {


filteredDmlDisabledCount is incremented before applying ShouldIncludeEntity(entityName, entityFilter). When callers pass the entities filter argument, this can count (and later log) entities that were never requested, making the filtered/returned counts misleading. Consider moving the entityFilter check before this block, or only increment/log for entities that pass the filter.

Suggested change

if (entity.Mcp?.DmlToolEnabled == false)

{

filteredDmlDisabledCount++;

continue;

}

if (!ShouldIncludeEntity(entityName, entityFilter))

{

if (!ShouldIncludeEntity(entityName, entityFilter))

{

continue;

}

if (entity.Mcp?.DmlToolEnabled == false)

{

filteredDmlDisabledCount++;

Copilot · 2026-01-31T05:15:11Z

src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs

+                    logger?.LogInformation(
+                        "DescribeEntitiesTool: {FilteredCount} entity(ies) filtered with DML tools disabled (dml-tools: false). " +
+                        "These entities are not exposed via DML tools and do not appear in describe_entities response. " +
+                        "Returned {ReturnedCount} entities, filtered {FilteredCount}.",


The log template repeats the {FilteredCount} placeholder name twice and requires passing the same argument twice. Consider removing the duplicate placeholder (or renaming one of them) to avoid duplicate structured-log keys and to simplify the call site.

Suggested change

"Returned {ReturnedCount} entities, filtered {FilteredCount}.",

"Returned {ReturnedCount} entities, filtered {FilteredCountTotal}.",

Copilot · 2026-01-31T05:15:11Z

src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

+    /// <summary>
+    /// Tests for DescribeEntitiesTool filtering logic (GitHub issue #3043).
+    /// Ensures stored procedures with custom-tool enabled are excluded from describe_entities results
+    /// to prevent duplication (they appear in tools/list instead).
+    /// Regular entities (tables, views, non-custom-tool SPs) remain visible in describe_entities.
+    /// </summary>


The XML doc comments describe the behavior as “custom-tool stored procedures are excluded”, but the tests in this file also cover (and the implementation enforces) filtering any entity with dml-tools: false (including tables/views). Please update the class/test comments to match the actual behavior being validated.

Copilot · 2026-01-31T05:15:12Z

src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

+
+        /// <summary>
+        /// Test that NoEntitiesConfigured error is returned when runtime config truly has no entities.
+        /// This is different from AllEntitiesFilteredAsCustomTools where entities exist but are filtered.


This comment references AllEntitiesFilteredAsCustomTools, but the implementation/test suite uses AllEntitiesFilteredDmlDisabled. Please update the comment to avoid confusion.

Suggested change

/// This is different from AllEntitiesFilteredAsCustomTools where entities exist but are filtered.

/// This is different from AllEntitiesFilteredDmlDisabled where entities exist but are filtered.

Copilot · 2026-01-31T05:15:12Z

src/Service.Tests/Mcp/DescribeEntitiesFilteringTests.cs

+        /// Verifies that when some (but not all) entities are filtered as custom-tool-only,
+        /// the filtering is logged but does not affect the response content.
+        /// The response should contain only the non-filtered entities.
+        /// </summary>
+        [TestMethod]
+        public async Task DescribeEntities_LogsFilteringInfo_WhenSomeEntitiesFiltered()


DescribeEntities_LogsFilteringInfo_WhenSomeEntitiesFiltered doesn’t currently assert anything about logging (it only validates response content/count). Either capture/assert log output (e.g., via a test logger) or rename/reword the test to reflect what it actually verifies.

Suggested change

/// Verifies that when some (but not all) entities are filtered as custom-tool-only,

/// the filtering is logged but does not affect the response content.

/// The response should contain only the non-filtered entities.

/// </summary>

[TestMethod]

public async Task DescribeEntities_LogsFilteringInfo_WhenSomeEntitiesFiltered()

/// Verifies that when some (but not all) entities are configured as custom-tool-only,

/// those entities are filtered from the describe_entities response while others remain.

/// The response should contain only the non-filtered entities and the count should match.

/// </summary>

[TestMethod]

public async Task DescribeEntities_FiltersCustomToolOnlyEntities_WhenSomeEntitiesFiltered()

[MCP] Prevent duplicating tool list between custom tools and describe…

0a4c986

…_entities

souvikghosh04 requested a review from Copilot January 22, 2026 08:14

Copilot started reviewing on behalf of souvikghosh04 January 22, 2026 08:14 View session

souvikghosh04 self-assigned this Jan 22, 2026

souvikghosh04 added mssql an issue thats specific to mssql mcp-server labels Jan 22, 2026

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github-project-automation bot moved this to Todo in Data API builder Jan 22, 2026

souvikghosh04 added this to the Jan 2026 milestone Jan 22, 2026

souvikghosh04 linked an issue Jan 22, 2026 that may be closed by this pull request

MCP-CustomTool: describe_entities filtering #3043

Open

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Minor fixes and refactoring

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souvikghosh04 requested a review from Copilot January 22, 2026 08:45

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souvikghosh04 added 2 commits January 22, 2026 14:26

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c793712

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souvikghosh04 marked this pull request as ready for review January 22, 2026 10:46

souvikghosh04 requested review from Alekhya-Polavarapu, Aniruddh25, RubenCerna2079, aaronburtle, anushakolan, neeraj-sharma2592, rusamant, sourabh1007 and vadeveka as code owners January 22, 2026 10:46

JerryNixon added the do-not-merge label Jan 22, 2026

Fix behavior of dmltools and custom tools combinations

e2cc3e8

souvikghosh04 removed the do-not-merge label Jan 22, 2026

souvikghosh04 changed the title ~~[MCP] Prevent duplicating tool list between custom tools and describe~~ Jan 23, 2026

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souvikghosh04 added 3 commits January 29, 2026 15:27

Merge branch 'main' of https://github.com/Azure/data-api-builder into…

a2f95a5

… Usr/sogh/describeentitiesfilter

Refactoring tests and implementing review comment suggesstions

4376db7

Merge branch 'main' of https://github.com/Azure/data-api-builder into…

4f6fff5

… Usr/sogh/describeentitiesfilter

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[MCP] Prevent duplicating entities between custom tools and describe_entities #3076

[MCP] Prevent duplicating entities between custom tools and describe_entities #3076

souvikghosh04 commented Jan 22, 2026 •

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	"Returned {ReturnedCount} entities, filtered {FilteredCount}.",
	"Returned {ReturnedCount} entities, filtered {FilteredCountTotal}.",

	/// This is different from AllEntitiesFilteredAsCustomTools where entities exist but are filtered.
	/// This is different from AllEntitiesFilteredDmlDisabled where entities exist but are filtered.

[MCP] Prevent duplicating entities between custom tools and describe_entities #3076

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[MCP] Prevent duplicating entities between custom tools and describe_entities #3076

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souvikghosh04 commented Jan 22, 2026 •

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