From 29b369326e5306dacf7bbe62a770101c82c2dc82 Mon Sep 17 00:00:00 2001
From: Shutkov Maksim <shutkov.maksim@mail.ru>
Date: Tue, 24 Feb 2026 16:10:46 +0300
Subject: [PATCH 1/2] update base ruby logic and settings for supporting ruby
 2.6

---
 .github/workflows/ci.yml | 1 +
 .rubocop.yml             | 2 +-
 lib/mcp/prompt.rb        | 2 +-
 lib/mcp/server.rb        | 5 ++++-
 mcp.gemspec              | 2 +-
 5 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9077935..fb28d88 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ jobs:
     strategy:
       matrix:
         entry:
+          - { ruby: '2.6', allowed-failure: false }
           - { ruby: '2.7', allowed-failure: false }
           - { ruby: '3.0', allowed-failure: false }
           - { ruby: '3.1', allowed-failure: false }
diff --git a/.rubocop.yml b/.rubocop.yml
index 2120de4..d2b3632 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -6,7 +6,7 @@ plugins:
   - rubocop-rake
 
 AllCops:
-  TargetRubyVersion: 2.7
+  TargetRubyVersion: 2.6
 
 Gemspec/DevelopmentDependencies:
   Enabled: true
diff --git a/lib/mcp/prompt.rb b/lib/mcp/prompt.rb
index 128ee47..03b81c3 100644
--- a/lib/mcp/prompt.rb
+++ b/lib/mcp/prompt.rb
@@ -114,7 +114,7 @@ def validate_arguments!(args)
       private
 
       def required_args
-        arguments_value.filter_map { |arg| arg.name.to_sym if arg.required }
+        arguments_value.map { |arg| arg.name.to_sym if arg.required }.compact
       end
     end
   end
diff --git a/lib/mcp/server.rb b/lib/mcp/server.rb
index 80cacd6..ee5049f 100644
--- a/lib/mcp/server.rb
+++ b/lib/mcp/server.rb
@@ -254,7 +254,10 @@ def validate!
     end
 
     def validate_tool_name!
-      duplicated_tool_names = @tool_names.tally.filter_map { |name, count| name if count >= 2 }
+      duplicated_tool_names = @tool_names
+        .each_with_object(Hash.new(0)) { |name, counts| counts[name] += 1 }
+        .select { |_name, count| count >= 2 }
+        .keys
 
       raise ToolNotUnique, duplicated_tool_names unless duplicated_tool_names.empty?
     end
diff --git a/mcp.gemspec b/mcp.gemspec
index b1f7667..c0141e4 100644
--- a/mcp.gemspec
+++ b/mcp.gemspec
@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
   spec.license       = "Apache-2.0"
 
   # Since this library is used by a broad range of users, it does not align its support policy with Ruby's EOL.
-  spec.required_ruby_version = ">= 2.7.0"
+  spec.required_ruby_version = ">= 2.6.0"
 
   spec.metadata["allowed_push_host"] = "https://rubygems.org"
   spec.metadata["changelog_uri"] = "https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v#{spec.version}"

From 3e98ccd2c1f61a953b841f340351f60e6c2fee52 Mon Sep 17 00:00:00 2001
From: Shutkov Maksim <shutkov.maksim@mail.ru>
Date: Tue, 24 Feb 2026 16:28:06 +0300
Subject: [PATCH 2/2] improved

---
 mcp.gemspec | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mcp.gemspec b/mcp.gemspec
index c0141e4..55dad0a 100644
--- a/mcp.gemspec
+++ b/mcp.gemspec
@@ -31,5 +31,5 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency("json-schema", ">= 4.1")
+  spec.add_dependency("json-schema", ">= 4.1", "< 6.0")
 end