fix: calling mcp server when calling wihtout any tool name and add integration test case

src/const.ts

@@ -65,6 +65,8 @@ export const SKYFIRE_PAY_ID_PROPERTY_DESCRIPTION = `Skyfire PAY token ID used fo
 
 export const SKYFIRE_README_CONTENT = `The Apify MCP Server allows clients to interact with Apify Actors, storage, and documentation. Before running any Apify Actor, you need to set up a Skyfire PAY token for billing purposes. To set up the PAY token you need to use the create-pay-token tool from the Skyfire MCP server. The PAY token must be charged with a minimum of ${SKYFIRE_MIN_CHARGE_USD} USD to be valid.${SKYFIRE_SELLER_ID ? ` The Skyfire seller ID for Apify MCP server is "${SKYFIRE_SELLER_ID}".` : ''} When running an Actor using the call-actor tool, you must provide the Skyfire PAY token ID in the \`skyfire-pay-id\` input property. Similarly, when retrieving Actor output using the get-actor-output tool, you must also provide the same Skyfire PAY token ID in the \`skyfire-pay-id\` input property.`;
 
+export const CALL_ACTOR_MCP_MISSING_TOOL_NAME_MSG = `When calling an MCP server Actor, you must specify the tool name in the actor parameter as "{actorName}:{toolName}" in the "actor" input property.`;
+
 // Cache
 export const ACTOR_CACHE_MAX_SIZE = 500;
 export const ACTOR_CACHE_TTL_SECS = 30 * 60; // 30 minutes

src/tools/actor.ts

@@ -8,6 +8,7 @@ import log from '@apify/log';
 import { ApifyClient } from '../apify-client.js';
 import {
     ACTOR_MAX_MEMORY_MBYTES,
+    CALL_ACTOR_MCP_MISSING_TOOL_NAME_MSG,
     HelperTools,
     RAG_WEB_BROWSER,
     RAG_WEB_BROWSER_ADDITIONAL_DESC,
@@ -384,8 +385,7 @@ EXAMPLES:
             // For definition resolution we always use token-based client; Skyfire is only for actual Actor runs
             const apifyClientForDefinition = new ApifyClient({ token: apifyToken });
             // Resolve MCP server URL
-            const needsMcpUrl = mcpToolName !== undefined || performStep === 'info';
-            const mcpServerUrlOrFalse = needsMcpUrl ? await getActorMcpUrlCached(baseActorName, apifyClientForDefinition) : false;
+            const mcpServerUrlOrFalse = await getActorMcpUrlCached(baseActorName, apifyClientForDefinition);
             const isActorMcpServer = mcpServerUrlOrFalse && typeof mcpServerUrlOrFalse === 'string';
 
             // Standby Actors, thus MCPs, are not supported in Skyfire mode
@@ -465,7 +465,7 @@ EXAMPLES:
                 // and does not provide the tool name.
                 const isMcpToolNameInvalid = mcpToolName === undefined || mcpToolName.trim().length === 0;
                 if (isActorMcpServer && isMcpToolNameInvalid) {
-                    return buildMCPResponse([`When calling an MCP server Actor, you must specify the tool name in the actor parameter as "{actorName}:{toolName}" in the "actor" input property.`]);
+                    return buildMCPResponse([CALL_ACTOR_MCP_MISSING_TOOL_NAME_MSG]);
                 }
 
                 // Handle MCP tool calls

tests/integration/suite.ts

@@ -4,7 +4,7 @@ import { CallToolResultSchema, ToolListChangedNotificationSchema } from '@modelc
 import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
 
 import { ApifyClient } from '../../src/apify-client.js';
-import { defaults, HelperTools } from '../../src/const.js';
+import { CALL_ACTOR_MCP_MISSING_TOOL_NAME_MSG, defaults, HelperTools } from '../../src/const.js';
 import { addTool } from '../../src/tools/helpers.js';
 import { defaultTools, toolCategories } from '../../src/tools/index.js';
 import { actorNameToToolName } from '../../src/tools/utils.js';
@@ -989,5 +989,25 @@ export function createIntegrationTestsSuite(
 
             await client.close();
         });
+
+        it.only('should return error message when tryging to call MCP server Actor without tool name in actor parameter', async () => {
+            client = await createClientFn({ tools: ['actors'] });
+
+            const response = await client.callTool({
+                name: 'call-actor',
+                arguments: {
+                    actor: ACTOR_MCP_SERVER_ACTOR_NAME,
+                    step: 'call',
+                    input: { url: 'https://docs.apify.com' },
+                },
+            });
+
+            expect(response.content).toBeDefined();
+            const content = response.content as { text: string }[];
+            expect(content.length).toBeGreaterThan(0);
+            expect(content[0].text).toContain(CALL_ACTOR_MCP_MISSING_TOOL_NAME_MSG);
+
+            await client.close();
+        });
     });
 }