fix(skill-mcp): use correct sessionID when registering skill MCP connections

Fixes #3021

src/tools/skill/tools.test.ts

@@ -172,6 +172,34 @@ describe("skill tool - MCP schema display", () => {
   })
 
   describe("formatMcpCapabilities with inputSchema", () => {
+    it("uses the tool context sessionID when the fallback getter is empty", async () => {
+      // given
+      loadedSkills = [
+        createMockSkillWithMcp("test-skill", {
+          playwright: { command: "npx", args: ["-y", "@anthropic-ai/mcp-playwright"] },
+        }),
+      ]
+
+      const listToolsSpy = spyOn(manager, "listTools").mockResolvedValue([])
+      spyOn(manager, "listResources").mockResolvedValue([])
+      spyOn(manager, "listPrompts").mockResolvedValue([])
+
+      const tool = createSkillTool({
+        skills: loadedSkills,
+        mcpManager: manager,
+        getSessionID: () => "",
+      })
+
+      // when
+      await tool.execute({ name: "test-skill" }, mockContext)
+
+      // then
+      expect(listToolsSpy).toHaveBeenCalledWith(
+        expect.objectContaining({ sessionID: mockContext.sessionID }),
+        expect.any(Object),
+      )
+    })
+
     it("displays tool inputSchema when available", async () => {
       // given
       const mockToolsWithSchema: McpTool[] = [

src/tools/skill/tools.ts

@@ -1,5 +1,6 @@
 import { dirname } from "node:path"
 import { tool, type ToolDefinition } from "@opencode-ai/plugin"
+import type { ToolContext } from "@opencode-ai/plugin/tool"
 import { TOOL_DESCRIPTION_NO_SKILLS, TOOL_DESCRIPTION_PREFIX } from "./constants"
 import type { SkillArgs, SkillInfo, SkillLoadOptions } from "./types"
 import type { LoadedSkill } from "../../features/opencode-skill-loader"
@@ -316,7 +317,7 @@ export function createSkillTool(options: SkillLoadOptions = {}): ToolDefinition
         .optional()
         .describe("Optional arguments or context for command invocation. Example: name='publish', user_message='patch'"),
     },
-    async execute(args: SkillArgs, ctx?: { agent?: string }) {
+    async execute(args: SkillArgs, ctx?: ToolContext) {
       const skills = await getSkills()
       const commands = getCommands()
       cachedDescription = formatCombinedDescription(skills.map(loadedSkillToInfo), commands)
@@ -359,11 +360,17 @@ export function createSkillTool(options: SkillLoadOptions = {}): ToolDefinition
           body,
         ]
 
-        if (options.mcpManager && options.getSessionID && matchedSkill.mcpConfig) {
+        if (options.mcpManager && matchedSkill.mcpConfig) {
+          const sessionID = ctx?.sessionID || options.getSessionID?.()
+
+          if (!sessionID) {
+            return output.join("\n")
+          }
+
           const mcpInfo = await formatMcpCapabilities(
             matchedSkill,
             options.mcpManager,
-            options.getSessionID()
+            sessionID
           )
           if (mcpInfo) {
             output.push(mcpInfo)

src/tools/skill/types.ts

@@ -29,7 +29,7 @@ export interface SkillLoadOptions {
   /** MCP manager for querying skill-embedded MCP servers */
   mcpManager?: SkillMcpManager
   /** Session ID getter for MCP client identification */
-  getSessionID?: () => string
+  getSessionID?: () => string | undefined
   /** Git master configuration for watermark/co-author settings */
   gitMasterConfig?: GitMasterConfig
   disabledSkills?: Set<string>