Added missing stored procedure parameters in describe_entities response. by anushakolan · Pull Request #3425 · Azure/data-api-builder

anushakolan · 2026-04-09T23:25:49Z

Why make this change?

Closes #3400.

describe_entities could return stored procedure entities with empty or partial parameters metadata when parameters were not fully listed in config. This caused MCP clients/agents to miss required inputs and fail execute_entity calls.

Additional discussion: #3400 issue thread.

What is this change?

Updated DescribeEntitiesTool to include stored procedure parameters from runtime DB metadata.
Merged DB metadata with config metadata so config values override matching fields (required, default, description).
Preserved fallback behavior: if metadata resolution fails, config-defined parameters are still returned.
Added focused MCP tests for:
- metadata-only parameter discovery
- config-overrides-DB merge behavior

How was this tested?

Integration Tests
Unit Tests

Ran:

dotnet test src/Service.Tests/Azure.DataApiBuilder.Service.Tests.csproj --filter "FullyQualifiedName~DescribeEntitiesStoredProcedureParametersTests"

Sample Request(s)

MCP request example:

describe_entities with full metadata:
- {"name":"describe_entities","arguments":{}}
execute_entity using discovered parameters:
- {"name":"execute_entity","arguments":{"entity":"GetBook","parameters":{"id":1}}}

Copilot

Pull request overview

Updates MCP describe_entities to reliably include complete stored procedure parameter metadata by augmenting/merging config-defined parameters with runtime database metadata, and adds targeted tests to validate the behavior.

Changes:

Resolve stored procedure parameter metadata from runtime DB metadata when config parameters are missing/partial.
Merge config + DB parameter metadata, preferring config values for overlapping fields.
Add MCP unit tests covering metadata-only discovery and config-overrides-DB merging.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs	Adds metadata resolution for stored procedure entities and merges DB/config parameter metadata in `describe_entities` output.
src/Service.Tests/Mcp/DescribeEntitiesStoredProcedureParametersTests.cs	Adds unit tests validating parameter discovery from DB metadata and config-overrides behavior.

Aniruddh25

Want to know reasoning behind why the bug happened.

Aniruddh25 · 2026-04-10T21:40:30Z

+
+            if (databaseObject is DatabaseStoredProcedure storedProcedure)
+            {
+                foreach ((string parameterName, ParameterDefinition parameterDefinition) in storedProcedure.StoredProcedureDefinition.Parameters)


What was the reason again to have two different data structures? ParameterDefinitionand ParameterMetadata? why couldnt we have used ParameterDefinition for the config parameters?

ParameterDefinition is runtime metadata discovered from the database. ParameterMetadata is user-specified config overrides. Both exist because DB metadata provides the source of truth for parameters, while config allows users to enrich with descriptions/defaults.

I understand we need both the objects. My question is - why couldnt we have expanded ParameterDefinition - the same data structure to support user specified config overrides? Why did we introduce a new class ParameterMetadata = also, the name is confusing.

Parameter information from DB metadata is called ParameterDefinition and not ParameterMetadata.

RubenCerna2079 · 2026-04-13T16:23:55Z

Hey just wanted to let you know that it seems this PR is related to a bug that I created for 2.0. Might be a good idea to check it and see if it can be fixed on this PR or as a follow up. #3435

anushakolan · 2026-04-17T00:51:13Z

Hey just wanted to let you know that it seems this PR is related to a bug that I created for 2.0. Might be a good idea to check it and see if it can be fixed on this PR or as a follow up. #3435

Thanks for linking these! They share the same root cause: parameter metadata is read only from config, not from runtime DB metadata.

PR #3425 fixes describe_entities (AI agents can now discover parameters).

Bug #3435 needs a follow-up PR to fix DynamicCustomTool.BuildInputSchema() the same way - it currently only reads Entity.Source.Parameters from config, not from IMetadataProviderFactory.

The fix requires passing IServiceProvider through CustomMcpToolFactory to DynamicCustomTool so it can access runtime metadata for schema building.

anushakolan · 2026-04-17T00:55:00Z

Want to know reasoning behind why the bug happened.

Original implementation only read config (Entity.Source.Parameters), ignoring runtime-discovered parameters from IMetadataProviderFactory. The fix merges both: DB metadata as base, config as overrides. May be @souvikghosh04 can add anything I missed.

…_params

souvikghosh04 · 2026-04-20T06:24:52Z

Want to know reasoning behind why the bug happened.

Original implementation only read config (Entity.Source.Parameters), ignoring runtime-discovered parameters from IMetadataProviderFactory. The fix merges both: DB metadata as base, config as overrides. May be @souvikghosh04 can add anything I missed.

I think we are discussing two separate things-

This PR: based on what I see the PR is trying to achieve is its merging the DB metadata (a new and additional pull) and the config defined metadata. but this creates inconsistency- discovery will surface DB-discovered params that tools still reject/don't advertise (since they validate against config only).
Issue [Bug]: Custom-tools that require parameters cannot be run #3435: It is mentioned in the description that the custom tool cannot be run for stored procedures which requires parameters. This is not correct. custom tool implementation (PR Implementation of Custom Tool in MCP #3048) correctly handles dynamic parameters when they're passed. Please refer to the sample JSON requests in the mentioned PR and see if those are supported in MCP Inspector. If not, you can use Insomnia client or stdio (GHCP) to test.

so for point 1- we might not need this PR unless we want to move completely to DB based discoverability to avoid split brain or incosistent behaviour.
for point 2- seems unrelated to this and probably should be closed since custom tool already support dynamic parameters based on what is configured in config during elevation of a stored proc as custom tool.

Aniruddh25 · 2026-04-20T17:24:13Z

                foreach (ParameterMetadata configParameter in configParameters.Values)
                {
-                    if (!storedProcedure.StoredProcedureDefinition.Parameters.ContainsKey(configParameter.Name))
+                    if (!storedProcedureParameters.ContainsKey(configParameter.Name) &&


why cant the ContainsKey comparison itself be case insensitive instead of adding another && condition?

On second thought, all configParameters should be present in the metadata retrieved from the database. In fact, config parameters should be a subset of database parameters.

There might a validation check to ensure this.

Aniruddh25 · 2026-04-20T18:02:25Z

+
+                foreach ((string parameterName, ParameterDefinition parameterDefinition) in storedProcedureParameters)
+                {
+                    configParameters.TryGetValue(parameterName, out ParameterMetadata? configParameter);


PR description says -

Merged DB metadata with config metadata so config values override matching fields (required, default, description).

However, this is not what is implemented.

With the current implementation, config values will never be added to the result since ALL config parameters should be discoverable in storedProcedureParameters by definition.
But the current check !storedProcedureParameters.ContainsKey(configParameter.Name) tries to identify the missing ones.

Config metadata should only be used to override, which means after reading params from DB metadata, the config values should be used to replace the values from DB.

Aniruddh25 · 2026-04-20T18:07:27Z

+            Assert.AreEqual(2, parameters.GetArrayLength());
+
+            JsonElement idParam = parameters.EnumerateArray().Single(p => p.GetProperty("name").GetString() == "id");
+            Assert.IsFalse(idParam.GetProperty("required").GetBoolean(), "DB required metadata should be preferred when config cannot indicate whether 'required' was explicitly set.");


The test is titled DescribeEntities_ConfigParameterMetadataOverridesDatabaseParameterMetadata
whereas this assert is doing exactly the opposite - DB is overriding config?

Assert should be Assert.IsTrue

Added missing stored procedure parameters in describe_entities response.

c5056bb

Copilot AI review requested due to automatic review settings April 9, 2026 23:25

anushakolan requested review from Alekhya-Polavarapu, Aniruddh25, JerryNixon, RubenCerna2079, aaronburtle, rusamant, sourabh1007, souvikghosh04, stuartpa and vadeveka as code owners April 9, 2026 23:25

anushakolan added the assign-for-review label Apr 9, 2026

Copilot started reviewing on behalf of anushakolan April 9, 2026 23:26 View session

Copilot AI reviewed Apr 9, 2026

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Comment thread src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs Outdated

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

Comment thread src/Azure.DataApiBuilder.Mcp/BuiltInTools/DescribeEntitiesTool.cs Outdated

anushakolan assigned Aniruddh25 and souvikghosh04 Apr 9, 2026

Aniruddh25 requested changes Apr 10, 2026

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souvikghosh04 unassigned Aniruddh25 and souvikghosh04 Apr 13, 2026

github-actions bot assigned aaronburtle and Aniruddh25 Apr 13, 2026

github-actions bot removed the assign-for-review label Apr 13, 2026

anushakolan added 2 commits April 16, 2026 18:26

Addressed comments

05284c7

Merge branch 'main' into dev/anushakolan/describe_entities_missing_sp…

36ef7c0

…_params

Aniruddh25 reviewed Apr 20, 2026

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anushakolan commented Apr 9, 2026

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