Add MCP tool to list functions (#9369)

* add list_functions tool for mcp

* adds list_function to index.ts

* fix linting errors

* switch readOnlyHint to true

* Update src/mcp/tools/functions/list_functions.ts

Co-authored-by: Daniel Lee <[email protected]>

* Update src/mcp/tools/functions/list_functions.ts

Co-authored-by: Daniel Lee <[email protected]>

* update changelog

* cleaned up formatting errors with prettier

---------

Co-authored-by: Daniel Lee <[email protected]>

Author: brittanycho

CHANGELOG.md

@@ -0,0 +1 @@
+- Added `functions.list_functions` as a MCP tool (#9369)

src/mcp/tools/functions/index.ts

@@ -1,5 +1,6 @@
 import type { ServerTool } from "../../tool";
 
 import { get_logs } from "./get_logs";
+import { list_functions } from "./list_functions";
 
-export const functionsTools: ServerTool[] = [get_logs];
+export const functionsTools: ServerTool[] = [get_logs, list_functions];

src/mcp/tools/functions/list_functions.ts

@@ -0,0 +1,58 @@
+import { z } from "zod";
+
+import { tool } from "../../tool";
+import { mcpError, toContent } from "../../util";
+import * as backend from "../../../deploy/functions/backend";
+import { getErrMsg } from "../../../error";
+import * as args from "../../../deploy/functions/args";
+
+export const list_functions = tool(
+  "functions",
+  {
+    name: "list_functions",
+    description: "List all deployed functions in your Firebase project.",
+    inputSchema: z.object({}),
+    annotations: {
+      title: "List Deployed Functions",
+      readOnlyHint: true,
+      openWorldHint: true,
+    },
+    _meta: {
+      requiresAuth: true,
+      requiresProject: true,
+    },
+  },
+  async (_, { projectId }) => {
+    const context = {
+      projectId,
+    } as args.Context;
+
+    try {
+      // fetches info about all currently deployed functions for the project
+      const existing = await backend.existingBackend(context);
+      // extracts all the function endpoints and sorts them
+      const endpointsList = backend.allEndpoints(existing).sort(backend.compareFunctions);
+
+      // below format differs from Firebase CLI command output to be more suitable format for agents
+      const formattedList = endpointsList.map((endpoint) => ({
+        function: endpoint.id,
+        version: endpoint.platform === "gcfv2" ? "v2" : "v1",
+        trigger: backend.endpointTriggerType(endpoint),
+        location: endpoint.region,
+        memory: endpoint.availableMemoryMb || "---",
+        runtime: endpoint.runtime,
+      }));
+
+      if (!formattedList.length) {
+        return toContent([], {
+          contentPrefix: "No functions found in this project.\n\n",
+        });
+      }
+
+      return toContent(formattedList);
+    } catch (err) {
+      const errMsg = getErrMsg((err as any)?.original || err, "Failed to list functions.");
+      return mcpError(errMsg);
+    }
+  },
+);