Unleash MCP (Feature Toggle)

Instructions

Implementation Reference

• src/tools/create-flag.ts:24-76 (handler)

  The primary handler function that implements the core logic of the createFlag tool. It processes validated parameters, invokes the Unleash API helper, handles success/error cases, and returns MCP-formatted content.

  export async function handleCreateFlag(params: {
    name: string;
    project: string;
    description?: string;
    type?: string;
    impressionData?: boolean;
  }) {
    try {
      // Create the feature flag
      const result = await createFeatureFlag({
        name: params.name,
        project: params.project,
        description: params.description,
        type: params.type,
        impressionData: params.impressionData
      });
      
      if (!result) {
        return {
          content: [{ 
            type: "text", 
            text: JSON.stringify({ 
              success: false,
              error: `Failed to create feature flag '${params.name}'` 
            }, null, 2)
          }],
          isError: true
        };
      }
      
      return {
        content: [{ 
          type: "text", 
          text: JSON.stringify({ 
            success: true,
            message: `Successfully created feature flag '${params.name}' in project '${params.project}'`,
            flag: result
          }, null, 2)
        }]
      };
    } catch (error: any) {
      return {
        content: [{ 
          type: "text", 
          text: JSON.stringify({ 
            success: false,
            error: error.message 
          }, null, 2)
        }],
        isError: true
      };
    }
  }

• src/tools/create-flag.ts:11-19 (schema)

  Zod-based input schema for validating parameters to the createFlag tool (name, project, description, type, impressionData).

  export const CreateFlagParamsSchema = {
    name: z.string().min(1).max(100).regex(/^[a-z0-9-_.]+$/, {
      message: "Name must be URL-friendly: use only lowercase, numbers, hyphens, underscores, and periods"
    }),
    project: z.string(),
    description: z.string().optional(),
    type: z.enum(['release', 'experiment', 'operational', 'permission', 'kill-switch']).optional(),
    impressionData: z.boolean().optional()
  };

• src/server.ts:94-99 (registration)

  Registers the createFlag tool with the MCP server instance using server.tool(), referencing the imported tool definition.

  server.tool(
    createFlagTool.name,
    createFlagTool.description,
    createFlagTool.paramsSchema as any,
    createFlagTool.handler as any
  );

• src/unleash/create-feature-flag.ts:20-42 (helper)

  Supporting helper utility that performs the actual HTTP POST request to the Unleash API to create the feature flag, handling payload preparation, logging, and error recovery.

  export async function createFeatureFlag(params: CreateFeatureFlagParams): Promise<any | null> {
    try {
      const payload = {
        name: params.name,
        description: params.description || '',
        type: params.type || 'release',
        impressionData: params.impressionData !== undefined ? params.impressionData : false
      };
  
      logger.info(`Creating feature flag: ${params.name} in project: ${params.project}`);
      
      const response = await client.post(
        `/api/admin/projects/${params.project}/features`,
        payload
      );
      
      logger.info(`Successfully created feature flag: ${params.name}`);
      return response.data;
    } catch (error: any) {
      logger.error(`Error creating feature flag ${params.name}:`, error.response?.data || error.message);
      return null;
    }
  } 

• src/tools/create-flag.ts:81-86 (registration)

  Tool definition object exporting the createFlag metadata (name, description, schema, handler) for use in MCP server registration.

  export const createFlagTool = {
    name: "createFlag",
    description: "Create a new feature flag in an Unleash project",
    paramsSchema: CreateFlagParamsSchema,
    handler: handleCreateFlag
  };