diff --git a/packages/coding-agent/scripts/measure-prompt-tokens.ts b/packages/coding-agent/scripts/measure-prompt-tokens.ts
new file mode 100644
index 000000000..f99cfb3cf
--- /dev/null
+++ b/packages/coding-agent/scripts/measure-prompt-tokens.ts
@@ -0,0 +1,63 @@
+import { countTokens } from "@oh-my-pi/pi-agent-core";
+import { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
+import { estimateToolSchemaTokens } from "@oh-my-pi/pi-coding-agent/modes/utils/context-usage";
+import { buildSystemPrompt } from "@oh-my-pi/pi-coding-agent/system-prompt";
+import { createTools, type Tool, type ToolSession } from "@oh-my-pi/pi-coding-agent/tools";
+
+function bytes(s: string): number {
+	return Buffer.byteLength(s, "utf-8");
+}
+function est(s: string): number {
+	return (bytes(s) + 3) >> 2;
+}
+
+await Settings.init({ inMemory: true, cwd: process.cwd() });
+const settings = Settings.isolated({});
+
+const session: ToolSession = {
+	cwd: process.cwd(),
+	hasUI: false,
+	getSessionFile: () => null,
+	getSessionSpawns: () => "*",
+	settings,
+} as ToolSession;
+
+const tools = await createTools(session);
+const toolsMap = new Map<string, Tool>(tools.map(t => [t.name, t]));
+
+console.log(`active tools (${tools.length}): ${tools.map(t => t.name).join(", ")}\n`);
+
+const rows: Array<{ name: string; descBytes: number; tok: number; schemaTok: number }> = [];
+for (const t of tools) {
+	const tok = estimateToolSchemaTokens([t as never]);
+	const descBytes = bytes(t.description ?? "");
+	const descTok = est(t.description ?? "");
+	rows.push({ name: t.name, descBytes, tok, schemaTok: tok - descTok });
+}
+rows.sort((a, b) => b.tok - a.tok);
+
+const totalTok = estimateToolSchemaTokens(tools as never);
+console.log("per-tool tokens (sorted): name | total tok | desc bytes | ~schema tok");
+for (const r of rows) {
+	console.log(
+		`  ${r.name.padEnd(20)} ${String(r.tok).padStart(6)}  ${String(r.descBytes).padStart(7)}  ${String(r.schemaTok).padStart(6)}`,
+	);
+}
+console.log(`\nTOOLS TOTAL tokens: ${totalTok}\n`);
+
+const built = await buildSystemPrompt({
+	tools: toolsMap as never,
+	toolNames: tools.map(t => t.name),
+	inlineToolDescriptors: false,
+	nativeTools: true,
+	cwd: process.cwd(),
+	skills: [],
+	contextFiles: [],
+	workspaceTree: { rootPath: process.cwd(), rendered: "", truncated: false, totalLines: 0, agentsMdFiles: [] },
+});
+const parts = built.systemPrompt;
+const part0 = parts[0] ?? "";
+const rest = parts.slice(1).join("\n");
+console.log(`system prompt parts: ${parts.length}`);
+console.log(`SYSTEM PROMPT tokens (part0, no skills): ${countTokens(part0)}  (bytes=${bytes(part0)})`);
+console.log(`SYSTEM CONTEXT tokens (parts[1..]): ${countTokens(rest)}  (bytes=${bytes(rest)})`);