Add base instructions to Radar MCP server

Author: andre-j3sus

apps/radar/src/context.ts

@@ -14,3 +14,28 @@ export interface Env {
 	DEV_CLOUDFLARE_API_TOKEN: string
 	DEV_CLOUDFLARE_EMAIL: string
 }
+
+export const BASE_INSTRUCTIONS = /* markdown */ `
+# Cloudflare Radar MCP Server
+
+This server integrates tools powered by the Cloudflare Radar API to provide insights into global Internet traffic,
+trends, and other related utilities.
+
+An active account is **only required** for URL Scanner-related tools (e.g., \`scan_url\`).
+
+For tools related to Internet trends and insights, analyze the results and, when appropriate, generate visualizations
+such as XY charts, pie charts, bar charts, or other relevant chart types.
+
+### Making comparisons
+
+Many tools support **array-based filters** to enable comparisons across multiple criteria.
+In such cases, the array index corresponds to a distinct data series.
+For each data series, provide a corresponding \`dateRange\`, or alternatively a \`dateStart\` and \`dateEnd\` pair.
+Example: To compare HTTP traffic between Portugal and Spain over the last 7 days:
+- \`dateRange: ["7d", "7d"]\`
+- \`location: ["PT", "ES"]\`
+
+This applies to date filters and other filters that support comparison across multiple values.
+If a tool does **not** support array-based filters, you can achieve the same comparison by making multiple separate
+calls to the tool.
+`

apps/radar/src/index.ts

@@ -13,6 +13,7 @@ import { CloudflareMCPServer } from '@repo/mcp-common/src/server'
 import { registerAccountTools } from '@repo/mcp-common/src/tools/account'
 import { MetricsTracker } from '@repo/mcp-observability'
 
+import { BASE_INSTRUCTIONS } from './context'
 import { registerRadarTools } from './tools/radar'
 import { registerUrlScannerTools } from './tools/url-scanner'
 
@@ -58,6 +59,7 @@ export class RadarMCP extends McpAgent<Env, State, Props> {
 				name: this.env.MCP_SERVER_NAME,
 				version: this.env.MCP_SERVER_VERSION,
 			},
+			options: { instructions: BASE_INSTRUCTIONS },
 		})
 
 		registerAccountTools(this)

apps/radar/src/tools/radar.ts

@@ -188,9 +188,7 @@ export function registerRadarTools(agent: RadarMCP) {
 
 	agent.server.tool(
 		'get_domains_ranking',
-		'Get top or trending domains' +
-			'Use arrays to compare multiple filters — the array index determines which series each filter value belongs to.' +
-			'For each filter series, you must provide a corresponding `date`.',
+		'Get top or trending domains',
 		{
 			limit: PaginationLimitParam,
 			date: DateListParam.optional(),
@@ -267,10 +265,7 @@ export function registerRadarTools(agent: RadarMCP) {
 
 	agent.server.tool(
 		'get_http_requests_data',
-		'Retrieve HTTP requests traffic trends. ' +
-			'Use arrays to compare multiple filters — the array index determines which series each filter value belongs to.' +
-			'For each filter series, you must provide a corresponding `dateRange`, or a `dateStart`/`dateEnd` pair. ' +
-			'Analyze the results and generate visualizations when appropriate.',
+		'Retrieve HTTP requests traffic trends.',
 		{
 			dateRange: DateRangeArrayParam.optional(),
 			dateStart: DateStartArrayParam.optional(),
@@ -327,10 +322,7 @@ export function registerRadarTools(agent: RadarMCP) {
 
 	agent.server.tool(
 		'get_l7_attack_data',
-		'Retrieve application layer (L7) attack trends. ' +
-			'Use arrays to compare multiple filters — the array index determines which series each filter value belongs to.' +
-			'For each filter series, you must provide a corresponding `dateRange`, or a `dateStart`/`dateEnd` pair. ' +
-			'Analyze the results and generate visualizations when appropriate.',
+		'Retrieve application layer (L7) attack trends.',
 		{
 			dateRange: DateRangeArrayParam.optional(),
 			dateStart: DateStartArrayParam.optional(),