[MCP] Prevent duplicating entities between custom tools and describe_entities

[souvikghosh04]

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
}

[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.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

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

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[souvikghosh04]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 6 pipeline(s).

[JerryNixon]

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