Reddit MCP Server

Instructions

Implementation Reference

• src/tools/post-tools.ts:131-210 (handler)

  Primary MCP tool handler for 'create_post'. Takes parameters, calls RedditClient.createPost, formats response with post details and links, handles errors with localized messages.

  export async function createPost(params: {
    subreddit: string;
    title: string;
    content: string;
    is_self?: boolean;
  }) {
    const { subreddit, title, content, is_self = true } = params;
    const client = getRedditClient();
  
    if (!client) {
      throw new McpError(
        ErrorCode.InternalError,
        "Reddit client not initialized"
      );
    }
  
    try {
      console.log(
        `[Tool] Creating ${is_self ? "text" : "link"} post in r/${subreddit}: "${title}"`
      );
      
      const startTime = Date.now();
      const post = await client.createPost(subreddit, title, content, is_self);
      const endTime = Date.now();
      
      console.log(`[Tool] Post creation took ${endTime - startTime}ms`);
      
      const formattedPost = formatPostInfo(post);
  
      return {
        content: [
          {
            type: "text",
            text: `
  # ✅ Post créé avec succès !
  
  ## 📝 Détails du post
  - **Titre**: ${formattedPost.title}
  - **Subreddit**: r/${formattedPost.subreddit}
  - **Type**: ${formattedPost.type}
  - **ID**: ${post.id}
  - **Auteur**: u/${formattedPost.author}
  
  ## 🔗 Liens
  - **Lien complet**: ${formattedPost.links.fullPost}
  - **Permalink**: https://reddit.com${post.permalink}
  
  ## ⏰ Statut
  Votre post a été **publié avec succès** sur r/${formattedPost.subreddit} !
  
  ${is_self ? 
    `**Contenu**: ${content.substring(0, 200)}${content.length > 200 ? '...' : ''}` : 
    `**URL**: ${content}`
  }
            `,
          },
        ],
      };
    } catch (error: any) {
      console.error(`[Error] Error creating post: ${error}`);
      
      // Provide more specific error messages
      let errorMessage = `Échec de la création du post: ${error.message}`;
      
      if (error.message.includes('timeout')) {
        errorMessage = `⏰ Timeout lors de la création du post. Le post a peut-être été créé malgré tout - vérifiez votre profil Reddit.`;
      } else if (error.message.includes('authentication')) {
        errorMessage = `🔐 Problème d'authentification. Vérifiez vos credentials Reddit dans le fichier .env`;
      } else if (error.message.includes('rate limit')) {
        errorMessage = `⏱️ Limite de fréquence atteinte. Attendez quelques minutes avant de réessayer.`;
      } else if (error.message.includes('submission')) {
        errorMessage = `📝 Erreur de soumission. Vérifiez que le subreddit existe et que vous avez les permissions.`;
      }
      
      throw new McpError(
        ErrorCode.InternalError,
        errorMessage
      );
    }
  }

• src/index.ts:180-207 (registration)

  Tool registration in MCP server's listTools response, defining name, description, and input schema with required parameters subreddit, title, content.

    name: "create_post",
    description: "Create a new post in a subreddit",
    inputSchema: {
      type: "object",
      properties: {
        subreddit: {
          type: "string",
          description: "Name of the subreddit to post in",
        },
        title: {
          type: "string",
          description: "Title of the post",
        },
        content: {
          type: "string",
          description:
            "Content of the post (text for self posts, URL for link posts)",
        },
        is_self: {
          type: "boolean",
          description:
            "Whether this is a self (text) post (true) or link post (false)",
          default: true,
        },
      },
      required: ["subreddit", "title", "content"],
    },
  },

• src/index.ts:454-462 (registration)

  Dispatch handler in MCP server's CallToolRequestSchema switch statement, routing 'create_post' calls to tools.createPost with typed parameters.

  case "create_post":
    return await tools.createPost(
      toolParams as {
        subreddit: string;
        title: string;
        content: string;
        is_self?: boolean;
      }
    );

• src/client/reddit-client.ts:270-352 (helper)

  Core RedditClient helper method implementing the actual Reddit API submission for creating posts, handling authentication, API call to /api/submit, and post retrieval.

  async createPost(
    subreddit: string,
    title: string,
    content: string,
    isSelf: boolean = true
  ): Promise<RedditPost> {
    await this.authenticate();
  
    if (!this.username || !this.password) {
      throw new Error("User authentication required for posting");
    }
  
    try {
      console.log(`[Post] Creating post in r/${subreddit}: "${title}"`);
      
      const kind = isSelf ? "self" : "link";
      const params = new URLSearchParams();
      params.append("sr", subreddit);
      params.append("kind", kind);
      params.append("title", title);
      params.append(isSelf ? "text" : "url", content);
  
      const response = await this.api.post("/api/submit", params, {
        headers: {
          "Content-Type": "application/x-www-form-urlencoded",
        },
        timeout: 30000, // 30 seconds timeout
      });
  
      console.log(`[Post] Reddit API response:`, response.data);
  
      if (response.data.success) {
        const postId = response.data.data.id;
        const postName = response.data.data.name;
        console.log(`[Post] Post created successfully! ID: ${postId}, Name: ${postName}`);
        
        try {
          // Try to get the newly created post
          const newPost = await this.getPost(postId);
          console.log(`[Post] Successfully retrieved created post`);
          return newPost;
        } catch (getError) {
          console.log(`[Post] Could not retrieve post details, but post was created successfully`);
          // Return a basic post object if we can't retrieve the full details
          return {
            id: postId,
            title: title,
            author: this.username!,
            subreddit: subreddit,
            selftext: isSelf ? content : "",
            url: isSelf ? "" : content,
            score: 1,
            upvoteRatio: 1.0,
            numComments: 0,
            createdUtc: Math.floor(Date.now() / 1000),
            over18: false,
            spoiler: false,
            edited: false,
            isSelf: isSelf,
            linkFlairText: "",
            permalink: `/r/${subreddit}/comments/${postId}/`,
          };
        }
      } else {
        console.error(`[Post] Reddit API returned success=false:`, response.data);
        const errors = response.data.errors || [];
        const errorMsg = errors.length > 0 ? errors.join(", ") : "Unknown error";
        throw new Error(`Failed to create post: ${errorMsg}`);
      }
    } catch (error: any) {
      console.error(`[Error] Failed to create post in r/${subreddit}:`, error);
      
      if (error.response) {
        console.error(`[Error] Reddit API error response:`, error.response.data);
        throw new Error(`Failed to create post: ${error.response.data?.message || error.message}`);
      } else if (error.code === 'ECONNABORTED') {
        console.error(`[Error] Request timeout when creating post`);
        throw new Error(`Post creation timed out - check Reddit manually to see if it was created`);
      } else {
        throw new Error(`Failed to create post in r/${subreddit}: ${error.message}`);
      }
    }
  }