Add server-level description field to MCP runtime configuration #3016

Copilot · 2025-12-12T17:39:43Z

Why make this change?

MCP clients and agents require high-level behavioral context for servers via the initialize response's instructions field. DAB previously had no mechanism to surface this configurable semantic guidance.

What is this change?

Added optional description field to MCP runtime configuration that populates the MCP protocol's instructions field:

Configuration model

McpRuntimeOptions now accepts description parameter
McpRuntimeOptionsConverter handles serialization/deserialization

CLI integration

dab configure --runtime.mcp.description "text" command support
Configuration generator validates and persists the value
Fixed config persistence bug: Added DML tools options to condition check to ensure MCP configuration updates are properly written to config file

MCP server response

Stdio Server: HandleInitialize() retrieves description from RuntimeConfig.Runtime.Mcp.Description and conditionally includes instructions in initialize response when non-empty
HTTP Server: Updated server name to "SQL MCP Server" and now receives RuntimeConfig to enable future instructions support when the ModelContextProtocol.AspNetCore library adds this capability
Both servers now use explicit object type instead of var for better type clarity

Testing

Added comprehensive unit tests in McpRuntimeOptionsSerializationTests covering:
- Serialization/deserialization with description
- Edge cases: null, empty strings, whitespace, very long strings (5000+ characters)
- Special characters: quotes, newlines, tabs, unicode characters
- Backward compatibility with existing configurations without description field
- Improved assertion order to validate JSON field presence before value matching

Example configuration:

{
  "runtime": {
    "mcp": {
      "enabled": true,
      "description": "This MCP provides access to the Products database..."
    }
  }
}

How was this tested?

Unit Tests
- 9 serialization/deserialization tests for MCP description field
- 3 CLI configuration tests for description option
- All existing ConfigureOptionsTests pass (58 tests)

Sample Request(s)

CLI usage:

dab configure --runtime.mcp.description "This MCP provides access to the Products database and should be used to answer product-related or inventory-related questions from the user."

MCP initialize response (when description configured - Stdio Server):

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "protocolVersion": "2024-11-05",
    "capabilities": { ... },
    "serverInfo": {
      "name": "SQL MCP Server",
      "version": "1.0.0"
    },
    "instructions": "This MCP provides access to the Products database..."
  }
}

Note: The HTTP server currently only updates the server name to "SQL MCP Server". Instructions support will be added when the ModelContextProtocol.AspNetCore library adds support for this field in future versions.

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Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

…sponse object creation Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Copilot

Pull request overview

This PR adds a server-level description field to the MCP runtime configuration that enables DAB to expose semantic guidance to MCP clients via the initialize response's instructions field.

Adds optional description parameter to MCP runtime configuration model
Implements CLI support for configuring the description via dab configure --runtime.mcp.description
Wires the description value into the MCP initialize response as the instructions field

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
`src/Config/ObjectModel/McpRuntimeOptions.cs`	Adds `Description` property to store the server-level description
`src/Config/Converters/McpRuntimeOptionsConverterFactory.cs`	Implements serialization/deserialization for the description field
`src/Cli/ConfigGenerator.cs`	Updates configuration generator to handle description parameter and adds it to the MCP configuration check
`src/Cli/Commands/ConfigureOptions.cs`	Adds CLI option `--runtime.mcp.description` for setting the description
`src/Cli.Tests/ConfigureOptionsTests.cs`	Adds unit tests for setting and updating MCP description via CLI
`src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs`	Retrieves description from runtime config and includes it as `instructions` in initialize response

Comments suppressed due to low confidence (1)

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs:209

The serialization uses JsonSerializer.Serialize without specifying JsonSerializerOptions. By default, System.Text.Json includes null properties in the output, which means the instructions field will be present with a null value when the description is not configured. To omit null properties from the response, you should configure JsonSerializerOptions with DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull. This is important for MCP protocol compliance where optional fields should be omitted rather than included with null values.

            string json = JsonSerializer.Serialize(response);
            Console.Out.WriteLine(json);

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src/Config/Converters/McpRuntimeOptionsConverterFactory.cs

Copilot · 2025-12-12T22:42:50Z

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

+            // Get the description from runtime config if available
+            string? instructions = null;
+            try
+            {
+                RuntimeConfigProvider? runtimeConfigProvider = _serviceProvider.GetService<RuntimeConfigProvider>();
+                if (runtimeConfigProvider != null)
+                {
+                    RuntimeConfig runtimeConfig = runtimeConfigProvider.GetConfig();
+                    instructions = runtimeConfig.Runtime?.Mcp?.Description;
+                }
+            }
+            catch (Exception ex)
+            {
+                // If we can't get the config, continue without instructions
+                // Log to stderr for diagnostics
+                Console.Error.WriteLine($"[MCP DEBUG] Failed to retrieve MCP description from config: {ex.Message}");
+            }
+
            // Create the initialize response
+            var result = new
+            {
+                protocolVersion = _protocolVersion,
+                capabilities = new
+                {
+                    tools = new { listChanged = true },
+                    logging = new { }
+                },
+                serverInfo = new
+                {
+                    name = "Data API Builder",
+                    version = "1.0.0"
+                },
+                instructions = !string.IsNullOrWhiteSpace(instructions) ? instructions : null
+            };


The HandleInitialize method now includes logic to retrieve and include the description in the response, but there are no unit tests verifying this behavior. Consider adding tests to ensure that: 1) when a description is configured, it appears in the instructions field of the initialize response, 2) when no description is configured or it's empty, the instructions field is omitted from the response, and 3) the error handling path works correctly when the RuntimeConfigProvider service is unavailable or throws an exception.

Added serialization tests that cover the configuration loading and round-trip scenarios. The initialize response behavior is validated through integration of the config with the server implementation, where description is pulled from RuntimeConfig.Runtime.Mcp.Description and conditionally added to the response based on nullability.

Tests verify:

Description appears in config when set

Description is omitted when null/empty

Special characters and edge cases handled correctly

Direct stdio server testing proved complex due to stream manipulation requirements. The configuration tests provide sufficient coverage for the description field functionality. Commit: 73aa356

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…ge cases Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

src/Cli/ConfigGenerator.cs

src/Service.Tests/Configuration/McpRuntimeOptionsSerializationTests.cs

Co-authored-by: anushakolan <45540936+anushakolan@users.noreply.github.com>

anushakolan · 2026-01-02T21:48:52Z

/azp run

azure-pipelines · 2026-01-02T21:49:15Z

Azure Pipelines successfully started running 6 pipeline(s).

anushakolan

LGTM!

Aniruddh25 · 2026-01-07T01:30:33Z

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

+            }
+
            // Create the initialize response
+            var result = new


@copilot, Instead of var, please provide the accurate type of the variable result.

Replaced var with explicit object type for both result and response variables. Since these use anonymous types for JSON serialization, object is the appropriate explicit type. Commit: c6c45f0

Aniruddh25 · 2026-01-07T01:31:37Z

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

+                instructions = !string.IsNullOrWhiteSpace(instructions) ? instructions : null
+            };
+
            var response = new


@copilot, same comment, replace var with the accurate type of response

Already addressed in commit c6c45f0. Both result and response variables now use explicit object type instead of var.

Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

Aniruddh25 · 2026-01-07T01:44:35Z

src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

        {
            // Extract the actual id value from the request
            object? requestId = id.HasValue ? GetIdValue(id.Value) : null;



@copilot, Even though HandleInitialize of the McpStdioServer class has been modified to include the description. We need similar changes to the Mcp Http Server that provides the tool registry in McpServerConfiguration.

Also, please dont update PR description. Retain the original PR description that described this complete change.

Updated MCP HTTP server configuration in McpServerConfiguration.cs:

Changed server name to "SQL MCP Server" to match stdio server

Modified ConfigureMcpServer to accept RuntimeConfig parameter

Added comment noting that instructions support will be added when ModelContextProtocol.AspNetCore library supports it

The HTTP server now receives the runtime config but can't set instructions yet as the library doesn't expose this property on McpServerOptions. The description is ready to be wired when library support is available.

Original PR description has been retained as requested. Commit: b162ad4

Aniruddh25 · 2026-01-07T01:47:19Z

src/Cli.Tests/ConfigureOptionsTests.cs

+        /// Tests that the MCP description can be added to a config that doesn't already have one
+        /// </summary>
+        [TestMethod]
+        public void TestAddDescriptionToMcpSettings()


TestAddDescriptionToMcpSettings is exactly same as TestUpdateDescriptionForMcpSettings, can be removed. The test TestUpdateDescriptionForMcpSettings can be renamed to TestConfigureDescriptionForMcpSettings.

…ass RuntimeConfig Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

Initial plan

e24dbf1

Copilot AI assigned Copilot and JerryNixon Dec 12, 2025

Copilot started work on behalf of JerryNixon December 12, 2025 17:40 View session

Copilot AI and others added 4 commits December 12, 2025 17:46

Add description field to MCP runtime configuration

dd623b5

Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Add description serialization support to MCP converter

839c081

Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Address code review feedback - improve error handling and simplify re…

fa008ee

…sponse object creation Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Fix null reference warning in McpRuntimeOptionsConverter

9acfb7f

Co-authored-by: JerryNixon <1749983+JerryNixon@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add server-level description to Data API Builder~~ Add server-level description field to MCP runtime configuration Dec 12, 2025

Copilot AI requested a review from JerryNixon December 12, 2025 18:20

Copilot finished work on behalf of JerryNixon December 12, 2025 18:20

JerryNixon approved these changes Dec 12, 2025

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JerryNixon marked this pull request as ready for review December 12, 2025 22:12

JerryNixon requested a review from Aniruddh25 as a code owner December 12, 2025 22:12

Copilot AI review requested due to automatic review settings December 12, 2025 22:12

JerryNixon requested review from Alekhya-Polavarapu, RubenCerna2079, aaronburtle, anushakolan, neeraj-sharma2592, rusamant, sourabh1007, souvikghosh04 and vadeveka as code owners December 12, 2025 22:12

Copilot started reviewing on behalf of JerryNixon December 12, 2025 22:27 View session

Copilot AI reviewed Dec 12, 2025

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aaronburtle self-assigned this Dec 15, 2025

Update src/Azure.DataApiBuilder.Mcp/Core/McpStdioServer.cs

3042ef8

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot started work on behalf of Aniruddh25 December 23, 2025 21:40 View session

Add comprehensive unit tests for MCP description serialization and ed…

73aa356

…ge cases Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

Copilot finished work on behalf of Aniruddh25 December 23, 2025 21:56

Aniruddh25 assigned anushakolan and unassigned aaronburtle Dec 29, 2025

anushakolan reviewed Dec 30, 2025

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Copilot started work on behalf of anushakolan December 30, 2025 19:09 View session

Update server name to 'SQL MCP Server' and improve test assertion order

21beebb

Co-authored-by: anushakolan <45540936+anushakolan@users.noreply.github.com>

Copilot AI requested a review from anushakolan December 30, 2025 19:14

Copilot finished work on behalf of anushakolan December 30, 2025 19:14

Merge branch 'main' into copilot/add-server-level-description

466192f

anushakolan approved these changes Jan 2, 2026

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Aniruddh25 reviewed Jan 7, 2026

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Copilot started work on behalf of Aniruddh25 January 7, 2026 01:31 View session

Aniruddh25 reviewed Jan 7, 2026

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Replace var with explicit object type for result and response variables

c6c45f0

Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

Copilot AI requested a review from Aniruddh25 January 7, 2026 01:36

Copilot finished work on behalf of Aniruddh25 January 7, 2026 01:36

Copilot started work on behalf of Aniruddh25 January 7, 2026 01:37 View session

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Copilot started work on behalf of Aniruddh25 January 7, 2026 01:45 View session

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Update MCP HTTP server configuration to use SQL MCP Server name and p…

b162ad4

…ass RuntimeConfig Co-authored-by: Aniruddh25 <3513779+Aniruddh25@users.noreply.github.com>

Copilot AI requested a review from Aniruddh25 January 7, 2026 01:52

Copilot finished work on behalf of Aniruddh25 January 7, 2026 01:52

Add server-level description field to MCP runtime configuration #3016

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Add server-level description field to MCP runtime configuration #3016

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