gitlab-mcp-server

Instructions

Implementation Reference

• src/index.ts:331-344 (handler)

  Main MCP tool handler for 'create_branch': parses input schema, fetches default branch ref if not provided, calls GitLab API via gitlabApi.createBranch, and returns the branch details as JSON.

  case "create_branch": {
    const args = CreateBranchSchema.parse(request.params.arguments);
    let ref = args.ref;
    if (!ref) {
      ref = await gitlabApi.getDefaultBranchRef(args.project_id);
    }
  
    const branch = await gitlabApi.createBranch(args.project_id, {
      name: args.branch,
      ref
    });
  
    return { content: [{ type: "text", text: JSON.stringify(branch, null, 2) }] };
  }

• src/index.ts:156-161 (registration)

  Tool registration in ALL_TOOLS array, defining name, description, input schema, and readOnly flag.

  {
    name: "create_branch",
    description: "Create a new branch in a GitLab project",
    inputSchema: createJsonSchema(CreateBranchSchema),
    readOnly: false
  },

• src/schemas.ts:435-439 (schema)

  Zod schema for 'create_branch' tool input validation: requires project_id and branch, optional ref.

  export const CreateBranchSchema = z.object({
    project_id: z.string(),
    branch: z.string(),
    ref: z.string().optional()
  });

• src/gitlab-api.ts:119-146 (helper)

  GitLabApi helper method that performs the actual POST request to create a branch, handles response parsing and error throwing.

  async createBranch(
    projectId: string,
    options: z.infer<typeof CreateBranchOptionsSchema>
  ): Promise<GitLabReference> {
    const response = await fetch(
      `${this.apiUrl}/projects/${encodeURIComponent(projectId)}/repository/branches`,
      {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${this.token}`,
          "Content-Type": "application/json"
        },
        body: JSON.stringify({
          branch: options.name,
          ref: options.ref
        })
      }
    );
  
    if (!response.ok) {
      throw new McpError(
        ErrorCode.InternalError,
        `GitLab API error: ${response.statusText}`
      );
    }
  
    return GitLabReferenceSchema.parse(await response.json());
  }