MCP Environment & Installation Manager

Implementation Reference

• src/tools/watcher-tools.ts:183-216 (handler)

  Handler function for the 'localize-mcp-server' tool. Performs input validation (non-empty strings) and delegates the core logic to watcherService.updateServerConfig, returning success response or throwing errors.

    async ({ configPath, serverName, packageName }, extra) => {
      if (!configPath.trim()) {
        throw new Error("Config path cannot be empty");
      }
      
      if (!serverName.trim()) {
        throw new Error("Server name cannot be empty");
      }
      
      if (!packageName.trim()) {
        throw new Error("Package name cannot be empty");
      }
      
      const result = await watcherService.updateServerConfig(configPath, serverName, packageName);
      
      if (!result.success) {
        throw new Error(`Failed to update server configuration: ${result.error}`);
      }
      
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify({
              success: true,
              configPath,
              serverName,
              packageName
            }, null, 2)
          }
        ]
      };
    }
  );

• src/tools/watcher-tools.ts:178-182 (schema)

  Zod input schema defining the required parameters: configPath (string), serverName (string), packageName (string).

  {
    configPath: z.string().describe("Path to configuration file"),
    serverName: z.string().describe("Name of the server in the configuration"),
    packageName: z.string().describe("Package name to use")
  },

• src/tools/watcher-tools.ts:176-216 (registration)

  MCP server tool registration call for 'localize-mcp-server', specifying input schema and inline handler function.

  server.tool(
    "localize-mcp-server",
    {
      configPath: z.string().describe("Path to configuration file"),
      serverName: z.string().describe("Name of the server in the configuration"),
      packageName: z.string().describe("Package name to use")
    },
    async ({ configPath, serverName, packageName }, extra) => {
      if (!configPath.trim()) {
        throw new Error("Config path cannot be empty");
      }
      
      if (!serverName.trim()) {
        throw new Error("Server name cannot be empty");
      }
      
      if (!packageName.trim()) {
        throw new Error("Package name cannot be empty");
      }
      
      const result = await watcherService.updateServerConfig(configPath, serverName, packageName);
      
      if (!result.success) {
        throw new Error(`Failed to update server configuration: ${result.error}`);
      }
      
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify({
              success: true,
              configPath,
              serverName,
              packageName
            }, null, 2)
          }
        ]
      };
    }
  );

• src/services/watcher-service.ts:213-286 (helper)

  Supporting method in WatcherService that implements the core localization logic: verifies package installation, parses and updates MCP config to point to local bin/dist/index.js, persists changes, updates caches and references.

  async updateServerConfig(
    configPath: string,
    serverName: string,
    packageName: string
  ): Promise<ConfigUpdateResult> {
    try {
      // Check if package is installed
      const installedPackage = this.packageManager.getInstalledPackage(packageName);
      if (!installedPackage) {
        return {
          success: false,
          configPath,
          serverName,
          packageName,
          error: `Package not installed: ${packageName}`
        };
      }
      
      // Read the config file
      const config = await readJsonFileOrDefault<McpConfig>(configPath, { mcpServers: {} });
      
      // Check if server exists
      if (!config.mcpServers || !config.mcpServers[serverName]) {
        return {
          success: false,
          configPath,
          serverName,
          packageName,
          error: `Server not found in config: ${serverName}`
        };
      }
      
      // Update the command to use the local package
      const server = config.mcpServers[serverName];
      
      // If bin path exists, use that
      if (installedPackage.binPath) {
        server.command = 'node';
        server.args = [installedPackage.binPath];
      } else {
        // Otherwise, use node with the package's main file
        server.command = 'node';
        server.args = [path.join(installedPackage.localPath, 'dist/index.js')];
      }
      
      // Write the updated config
      await fs.writeFile(configPath, JSON.stringify(config, null, 2));
      
      // Update the cache
      this.configCache.set(configPath, config);
      
      // Add config reference
      await this.packageManager.addConfigReference(packageName, {
        path: configPath,
        platform: this.getPlatformForConfig(configPath),
        serverName
      });
      
      return {
        success: true,
        configPath,
        serverName,
        packageName
      };
    } catch (error) {
      return {
        success: false,
        configPath,
        serverName,
        packageName,
        error: error instanceof Error ? error.message : String(error)
      };
    }
  }