feat: MCPサーバー

記事の確認と投稿をClaudeCodeから直接行えるようにする

Author: takeyuweb

.devcontainer/devcontainer.json

@@ -39,6 +39,7 @@
   // Mount host's ~/.claude if it exists
   "mounts": [
     "source=${localEnv:HOME}/.claude,target=/home/vscode/.claude,type=bind,consistency=cached",
-    "source=${localEnv:HOME}/.claude.json,target=/home/vscode/.claude.json,type=bind,consistency=cached"
+    "source=${localEnv:HOME}/.claude.json,target=/home/vscode/.claude.json,type=bind,consistency=cached",
+    "source=${localEnv:HOME}/.mcp.json,target=/home/vscode/.mcp.json,type=bind,consistency=cached"
   ]
 }

.mcp.json

@@ -0,0 +1,5 @@
+{
+  "mcpServers": {
+    "spotlight-rails": {}
+  }
+}

Gemfile

@@ -75,3 +75,6 @@ gem "metainspector", "~> 5.15"
 gem "rswag-api"
 gem "rswag-ui"
 gem "rswag-specs", group: [ :development, :test ]
+
+# Model Context Protocol (MCP) for LLM integration
+gem "mcp"

Gemfile.lock

@@ -163,6 +163,7 @@ GEM
     json-schema (5.1.1)
       addressable (~> 2.8)
       bigdecimal (~> 3.1)
+    json_rpc_handler (0.1.1)
     kamal (2.5.2)
       activesupport (>= 7.0)
       base64 (~> 0.2)
@@ -186,6 +187,8 @@ GEM
       net-pop
       net-smtp
     marcel (1.0.4)
+    mcp (0.1.0)
+      json_rpc_handler (~> 0.1)
     metainspector (5.15.0)
       addressable (~> 2.8.4)
       faraday (~> 2.5)
@@ -457,6 +460,7 @@ DEPENDENCIES
   importmap-rails
   jbuilder
   kamal
+  mcp
   metainspector (~> 5.15)
   propshaft
   puma (>= 5.0)

README.md

@@ -41,3 +41,21 @@ bundle exec rails rswag:specs:swaggerize
 ```
 
 http://localhost:3000/api-docs/
+
+## MCP サーバー
+記事の更新のためのMCPサーバーを実装しています。
+
+```json:~/.mcp.json
+{
+  "mcpServers": {
+    "spotlight-rails": {
+      "type": "http",
+      "url": "https://takeyuweb.co.jp/api/mcp",
+      "method": "POST",
+      "headers": {
+        "Authorization": "Bearer token"
+      }
+    }
+  }
+}
+```

app/controllers/api/mcp_controller.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Api
+  class McpController < ApplicationController
+    skip_before_action :verify_authenticity_token
+    before_action :authenticate_mcp_request
+
+    def handle
+      # Create MCP server instance
+      server = ArticleServer.create
+
+      # Handle the JSON-RPC request
+      response = server.handle_json(request.raw_post)
+
+      # Return response
+      render json: response
+    rescue => e
+      Rails.logger.error "MCP Error: #{e.message}"
+      Rails.logger.error e.backtrace.join("\n")
+
+      render json: {
+        jsonrpc: "2.0",
+        error: {
+          code: -32603,
+          message: "Internal error",
+          data: { details: e.message }
+        },
+        id: nil
+      }, status: :internal_server_error
+    end
+
+    private
+
+    def authenticate_mcp_request
+      token = request.headers["Authorization"]&.gsub(/^Bearer\s+/, "")
+      expected_token = Rails.application.credentials.dig(:mcp, :api_token)
+
+      unless token.present? && ActiveSupport::SecurityUtils.secure_compare(token, expected_token)
+        render json: {
+          jsonrpc: "2.0",
+          error: {
+            code: -32603,
+            message: "Unauthorized",
+            data: { details: "Invalid or missing authentication token" }
+          },
+          id: params[:id]
+        }, status: :unauthorized
+      end
+    end
+  end
+end

app/mcp/article_server.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class ArticleServer
+  def self.create
+    MCP::Server.new(
+      name: "spotlight-rails-articles",
+      version: "1.0.0",
+      tools: [
+        Tools::CreateArticleTool,
+        Tools::UpdateArticleTool,
+        Tools::FindArticleTool
+      ],
+      server_context: {}
+    )
+  end
+end

app/mcp/tools/create_article_tool.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Tools
+  class CreateArticleTool < MCP::Tool
+    description "Create a new article from markdown content with YAML frontmatter"
+
+    input_schema(
+      properties: {
+        content: {
+          type: "string",
+          description: "The markdown content with YAML frontmatter (including title, slug, description, published_date, tags, etc.)"
+        }
+      },
+      required: [ "content" ]
+    )
+
+    def self.call(content:, server_context:)
+      article = Article.import_from_markdown(content)
+
+      if article
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Article created successfully:\n" \
+                "- Title: #{article.title}\n" \
+                "- Slug: #{article.slug}\n" \
+                "- Published at: #{article.published_at}\n" \
+                "- Tags: #{article.tags.pluck(:name).join(', ')}"
+        } ])
+      else
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Failed to create article. Please check the markdown content and ensure it has valid YAML frontmatter with required fields (title, slug, description, published_date)."
+        } ])
+      end
+    rescue => e
+      MCP::Tool::Response.new([ {
+        type: "text",
+        text: "Error creating article: #{e.message}"
+      } ])
+    end
+  end
+end

app/mcp/tools/find_article_tool.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Tools
+  class FindArticleTool < MCP::Tool
+    description "Find an article by slug and return its details"
+
+    input_schema(
+      properties: {
+        slug: {
+          type: "string",
+          description: "The slug of the article to find"
+        }
+      },
+      required: [ "slug" ]
+    )
+
+    def self.call(slug:, server_context:)
+      article = Article.find_by(slug: slug)
+
+      if article
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Article found:\n" \
+                "- Title: #{article.title}\n" \
+                "- Slug: #{article.slug}\n" \
+                "- Description: #{article.description}\n" \
+                "- Published at: #{article.published_at}\n" \
+                "- Tags: #{article.tags.pluck(:name).join(', ')}\n" \
+                "- Created at: #{article.created_at}\n" \
+                "- Updated at: #{article.updated_at}"
+        } ])
+      else
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Article not found with slug: #{slug}"
+        } ])
+      end
+    rescue => e
+      MCP::Tool::Response.new([ {
+        type: "text",
+        text: "Error finding article: #{e.message}"
+      } ])
+    end
+  end
+end

app/mcp/tools/update_article_tool.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Tools
+  class UpdateArticleTool < MCP::Tool
+    description "Update an existing article by slug with new markdown content"
+
+    input_schema(
+      properties: {
+        slug: {
+          type: "string",
+          description: "The slug of the article to update"
+        },
+        content: {
+          type: "string",
+          description: "The new markdown content with YAML frontmatter"
+        }
+      },
+      required: [ "slug", "content" ]
+    )
+
+    def self.call(slug:, content:, server_context:)
+      # Find the existing article
+      article = Article.find_by(slug: slug)
+
+      unless article
+        return MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Article not found with slug: #{slug}"
+        } ])
+      end
+
+      # Update the article with new content
+      updated_article = Article.import_from_markdown(content)
+
+      if updated_article
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Article updated successfully:\n" \
+                "- Title: #{updated_article.title}\n" \
+                "- Slug: #{updated_article.slug}\n" \
+                "- Published at: #{updated_article.published_at}\n" \
+                "- Tags: #{updated_article.tags.pluck(:name).join(', ')}"
+        } ])
+      else
+        MCP::Tool::Response.new([ {
+          type: "text",
+          text: "Failed to update article. Please check the markdown content and ensure it has valid YAML frontmatter."
+        } ])
+      end
+    rescue => e
+      MCP::Tool::Response.new([ {
+        type: "text",
+        text: "Error updating article: #{e.message}"
+      } ])
+    end
+  end
+end