GitLab MCP Server

Instructions

Implementation Reference

• src/handlers/merge-requests.ts:425-463 (handler)

  The handler function that executes the tool: creates a new discussion thread on a GitLab merge request, supporting inline diff positions, by calling the GitLab Discussions API endpoint.
  async createMRDiscussion(args: CreateMRDiscussionParams) { const requestData: Record<string, unknown> = { body: args.body, }; // Add position for inline/diff comments if (args.position) { requestData.position = { base_sha: args.position.base_sha, start_sha: args.position.start_sha, head_sha: args.position.head_sha, old_path: args.position.old_path, new_path: args.position.new_path, position_type: args.position.position_type || "text", ...(args.position.old_line !== undefined && { old_line: args.position.old_line, }), ...(args.position.new_line !== undefined && { new_line: args.position.new_line, }), }; } const data = await this.client.post( `/projects/${encodeURIComponent(args.project_id)}/merge_requests/${ args.merge_request_iid }/discussions`, requestData ); return { content: [ { type: "text", text: JSON.stringify(data, null, 2), }, ], }; }
• src/tools/merge-requests.ts:400-468 (schema)

  MCP tool definition including name, description, and inputSchema for validating parameters like project_id, merge_request_iid, body, and optional position for inline comments.
  { name: 'create_mr_discussion', description: 'Create a new discussion on a merge request. Can be a general discussion or an inline comment on the diff', inputSchema: { type: 'object', properties: { project_id: { type: 'string', description: 'Project ID or path', }, merge_request_iid: { type: 'number', description: 'Merge request internal ID', }, body: { type: 'string', description: 'The content of the discussion (supports Markdown)', }, position: { type: 'object', description: 'Position for inline/diff comments. Required fields: base_sha, start_sha, head_sha, old_path, new_path. Use new_line for additions, old_line for deletions, both for context lines.', properties: { base_sha: { type: 'string', description: 'Base commit SHA (merge request target branch HEAD)', }, start_sha: { type: 'string', description: 'SHA of the commit when the MR was created (typically same as base_sha)', }, head_sha: { type: 'string', description: 'HEAD commit SHA of the merge request source branch', }, old_path: { type: 'string', description: 'File path before the change (use same as new_path for new files)', }, new_path: { type: 'string', description: 'File path after the change', }, position_type: { type: 'string', enum: ['text'], description: 'Type of position (text for code comments)', default: 'text', }, old_line: { type: 'number', description: 'Line number in old version (for deleted lines or context)', }, new_line: { type: 'number', description: 'Line number in new version (for added lines or context)', }, }, required: ['base_sha', 'start_sha', 'head_sha', 'old_path', 'new_path'], }, }, required: ['project_id', 'merge_request_iid', 'body'], }, },
• src/server.ts:219-222 (registration)

  Server-side registration: switch case that dispatches tool calls to the mergeRequestHandlers.createMRDiscussion method.
  case "create_mr_discussion": return await this.mergeRequestHandlers.createMRDiscussion( args as unknown as CreateMRDiscussionParams );
• src/types.ts:491-505 (schema)

  TypeScript interface defining the input parameters for the createMRDiscussion handler, matching the tool schema.
  export interface CreateMRDiscussionParams { project_id: string; merge_request_iid: number; body: string; position?: { base_sha: string; start_sha: string; head_sha: string; old_path: string; new_path: string; position_type?: 'text'; old_line?: number; new_line?: number; }; }