Fix ResourceLinkBlock deserialization by adding missing "name" case

[Copilot]

Summary

Fixed a critical deserialization bug in ResourceLinkBlock where the "name" property was not being read from JSON, causing a JsonException to be thrown during deserialization.

Problem

When attempting to deserialize a ResourceLinkBlock from JSON, the following exception was thrown:

JsonException: Name must be provided for 'resource_link' type.

This occurred because the ContentBlock.Converter.Read method was missing a switch case for the "name" property, even though:

• The name variable was declared (line 75)
• The name property was being written correctly during serialization (line 245)
• The name variable was expected to be non-null when creating the ResourceLinkBlock (line 178)

Root Cause

In src/ModelContextProtocol.Core/Protocol/ContentBlock.cs, the switch statement in the Read method (lines 96-140) was missing a case for "name", causing the name property to remain null during deserialization.

Solution

Added the missing switch case to properly handle the "name" property during JSON deserialization:

case "name":
    name = reader.GetString();
    break;

Testing

• Manual testing confirmed that ResourceLinkBlock now serializes and deserializes correctly
• All required properties (uri, name) are preserved during round-trip serialization
• Optional properties (description, mimeType, size) are also handled correctly
• Added comprehensive test cases in ContentBlockTests.cs to prevent regression
• Verified that existing ContentBlock types (TextContentBlock, ImageContentBlock, etc.) continue to work correctly

Example

Before this fix:

var resourceLink = new ResourceLinkBlock { Uri = "https://example.com", Name = "Test" };
var json = JsonSerializer.Serialize(resourceLink, McpJsonUtilities.DefaultOptions);
var deserialized = JsonSerializer.Deserialize<ContentBlock>(json, McpJsonUtilities.DefaultOptions);
// ❌ Throws JsonException: Name must be provided for 'resource_link' type.

After this fix:

var resourceLink = new ResourceLinkBlock { Uri = "https://example.com", Name = "Test" };
var json = JsonSerializer.Serialize(resourceLink, McpJsonUtilities.DefaultOptions);
var deserialized = JsonSerializer.Deserialize<ContentBlock>(json, McpJsonUtilities.DefaultOptions);
// ✅ Works correctly, preserves all properties

Fixes #644.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• aka.ms
  • Triggering command: curl -I -sSL --retry 5 --retry-delay 2 --connect-timeout 15 REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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