diff --git a/src/buzz-mcp/tools.test.ts b/src/buzz-mcp/tools.test.ts
index be6d611b5b..978e8e6072 100644
--- a/src/buzz-mcp/tools.test.ts
+++ b/src/buzz-mcp/tools.test.ts
@@ -1006,7 +1006,15 @@ function relay(refused: Readonly<Record<string, string>> = {}) {
     }
     if (kind === 9000 || kind === 9021) {
       const key = kind === 9021 ? me : target;
-      const role = template.tags.find((t) => t[0] === "role")?.[1] ?? "member";
+      // Like the relay, with no role asked for a member keeps theirs and a
+      // new one gets the channel's join_role.
+      const tags = (kind: number) =>
+        state.find((e) => e.kind === kind && e.tags[0]?.[1] === id)?.tags ?? [];
+      const role =
+        template.tags.find((t) => t[0] === "role")?.[1] ??
+        tags(39002).find((t) => t[0] === "p" && t[1] === key)?.[3] ??
+        tags(39000).find((t) => t[0] === "join_role")?.[1] ??
+        "member";
       put(39002, id, (tags) => [...without(tags, key), ["p", key, "", role]]);
     }
     if (kind === 9001 || kind === 9022)
@@ -1720,9 +1728,29 @@ it("refuses channel arguments that do not fit, before publishing", async () => {
   await expect(
     channel("channel_create", { name: "x", visibility: "open", ttl: 1.5 }),
   ).rejects.toThrow("ttl must be a whole number of seconds.");
+  await expect(
+    channel("channel_create", {
+      name: "x",
+      visibility: "open",
+      join_role: "admin",
+    }),
+  ).rejects.toThrow("join_role must be member or guest.");
+  await expect(
+    channel("channel_create", {
+      name: "x",
+      visibility: "private",
+      join_role: "guest",
+    }),
+  ).rejects.toThrow("join_role guest is for open channels.");
+  await expect(
+    channel("channel_update", { visibility: "private", join_role: "guest" }),
+  ).rejects.toThrow("join_role guest is for open channels.");
   await expect(channel("channel_update", {})).rejects.toThrow(
-    "Give name, about, visibility, ttl, topic or purpose.",
+    "Give name, about, visibility, ttl, join_role, topic or purpose.",
   );
+  await expect(
+    channel("channel_update", { join_role: "owner" }),
+  ).rejects.toThrow("join_role must be member or guest.");
   await expect(
     callTool(client, { channel: "chan" }, "channel_leave", {}),
   ).rejects.toThrow("Invalid channel ID");
@@ -1760,6 +1788,151 @@ it("shows a channel's details and changes them as the channel shows", async () =
   );
 });
 
+it("makes a channel an announce channel and back", async () => {
+  const { client, published } = relay();
+  const context = { channel: room };
+  await expect(
+    callTool(client, context, "channel_update", { join_role: "guest" }),
+  ).resolves.toBe(`updated ${room}`);
+  await expect(callTool(client, context, "channel_get", {})).resolves.toBe(
+    `${room} plans (stream, open, join as guest)\nabout: roadmap\nyou: owner`,
+  );
+  await expect(
+    callTool(client, context, "channel_update", { join_role: "member" }),
+  ).resolves.toBe(`updated ${room}`);
+  expect(published.map((template) => template.tags)).toEqual([
+    [
+      ["h", room],
+      ["join_role", "guest"],
+    ],
+    [
+      ["h", room],
+      ["join_role", "member"],
+    ],
+  ]);
+});
+
+it("creates an announce channel after adding its template's agents", async () => {
+  const { client, published, state } = relay();
+  client.templates = vi.fn(async () => [
+    { name: "Team", canvas: "", agents: [alice] },
+  ]);
+  const answer = await callTool(client, {}, "channel_create", {
+    name: "team",
+    visibility: "open",
+    join_role: "guest",
+    template: "Team",
+  });
+  const id = published[0]?.tags[0]?.[1] as string;
+  // Set last: an agent added with no role would otherwise join as a guest.
+  expect(published.map((template) => [template.kind, template.tags])).toEqual([
+    [
+      9007,
+      [
+        ["h", id],
+        ["name", "team"],
+        ["visibility", "open"],
+        ["channel_type", "stream"],
+      ],
+    ],
+    [
+      9000,
+      [
+        ["h", id],
+        ["p", alice],
+      ],
+    ],
+    [
+      9002,
+      [
+        ["h", id],
+        ["join_role", "guest"],
+      ],
+    ],
+  ]);
+  expect(answer).toBe(
+    [
+      `created ${id}`,
+      `added ${alice} Alice Smith`,
+      "new people join as guests",
+    ].join("\n"),
+  );
+  await expect(
+    callTool(client, { channel: id }, "channel_get", {}),
+  ).resolves.toBe(`${id} team (stream, open, join as guest)\nyou: owner`);
+  const roster = () =>
+    state.find((e) => e.kind === 39002 && e.tags[0]?.[1] === id)?.tags;
+  expect(roster()).toContainEqual(["p", alice, "", "member"]);
+  // Now anyone added with no role is a guest, and the answer says so.
+  await expect(
+    callTool(client, { channel: id }, "members", { add: [bob] }),
+  ).resolves.toBe(`added ${bob} as guest`);
+  expect(roster()).toContainEqual(["p", bob, "", "guest"]);
+});
+
+it("sets join_role when the template's Canvas is refused, and says when it cannot", async () => {
+  const { client, published } = relay();
+  const publish = client.publish;
+  client.publish = vi.fn(async (template: Template) => {
+    if (template.kind === 40100) throw new Error("canvas refused");
+    return publish(template);
+  });
+  client.templates = vi.fn(async () => [
+    { name: "Team", canvas: "# Plan", agents: [alice] },
+  ]);
+  const create = () =>
+    callTool(client, {}, "channel_create", {
+      name: "team",
+      visibility: "open",
+      join_role: "guest",
+      template: "Team",
+    });
+  let answer = await create();
+  let id = published[0]?.tags[0]?.[1] as string;
+  expect(published.map((template) => template.kind)).toEqual([9007, 9002]);
+  expect(answer).toBe(
+    `created ${id}\nCanvas not started, so no agents were added: canvas refused\nnew people join as guests`,
+  );
+  const query = client.query;
+  client.query = vi.fn(async (filters: readonly Filter[]) => {
+    if (filters.some((f) => (f.kinds as number[]).includes(39000)))
+      throw new Error("kind 39000 unavailable");
+    return query(filters);
+  });
+  answer = await create();
+  id = published.at(-1)?.tags[0]?.[1] as string;
+  expect(published.at(-1)?.kind).toBe(9007);
+  expect(answer).toBe(
+    `The community accepted channel ${id} but its state could not be read back: kind 39000 unavailable; the template was not applied; join_role was not set.`,
+  );
+});
+
+it("reports a new channel whose join_role was refused", async () => {
+  const { client, published } = relay();
+  const publish = client.publish;
+  client.publish = vi.fn(async (template: Template) => {
+    if (template.kind === 9002) throw new Error("restricted: admins only");
+    return publish(template);
+  });
+  const answer = await callTool(client, {}, "channel_create", {
+    name: "news",
+    visibility: "open",
+    join_role: "guest",
+  });
+  const id = published[0]?.tags[0]?.[1] as string;
+  expect(published.map((template) => template.kind)).toEqual([9007]);
+  expect(answer).toBe(
+    `created ${id}\njoin_role not set: restricted: admins only`,
+  );
+  // member is the default, so it needs no second event.
+  await callTool(client, {}, "channel_create", {
+    name: "chat",
+    visibility: "open",
+    join_role: "member",
+  });
+  expect(published.map((template) => template.kind)).toEqual([9007, 9007]);
+});
+
 it("leaves, joins, archives, unarchives and deletes a channel", async () => {
   const { client, published } = relay();
   const context = { channel: room };
diff --git a/src/buzz-mcp/tools.ts b/src/buzz-mcp/tools.ts
index 63649ac2b4..ef4980c0c1 100644
--- a/src/buzz-mcp/tools.ts
+++ b/src/buzz-mcp/tools.ts
@@ -25,6 +25,7 @@ import { attestedOwner } from "../features/agents/owner-attestation";
 import type {
   BuzzClient,
   BuzzEvent,
+  ChannelTemplate,
   Context,
   Filter,
   Memory,
@@ -51,6 +52,12 @@ const ttl = {
   type: "integer",
   description: "Seconds without a message before it archives; 0: never.",
 } as const;
+const joinRole = {
+  type: "string",
+  enum: ["member", "guest"],
+  description:
+    "Role for people who join or are added without one. guest on an open channel: anyone reads, only members post.",
+} as const;
 const tool = (
   name: string,
   description: string,
@@ -185,6 +192,7 @@ export const TOOLS: readonly Tool[] = [
           "system: left out of ordinary channel lists; anyone can still list an open one.",
       },
       ttl,
+      join_role: joinRole,
       template: str,
     },
     ["name", "visibility"],
@@ -195,6 +203,7 @@ export const TOOLS: readonly Tool[] = [
     about: str,
     visibility: { type: "string", enum: ["open", "private"] },
     ttl,
+    join_role: joinRole,
     topic: str,
     purpose: str,
   }),
@@ -1356,6 +1365,7 @@ class Tools {
       tag(metadata, "ttl")
         ? `archives after ${tag(metadata, "ttl")}s idle`
         : "",
+      tag(metadata, "join_role") === "guest" ? "join as guest" : "",
     ].filter(Boolean);
     return [
       `${channel} ${tag(metadata, "name") ?? ""} (${flags.join(", ")})`,
@@ -1376,6 +1386,9 @@ class Tools {
     const type = args.type ?? "stream";
     if (type !== "stream" && type !== "forum" && type !== "system")
       throw new Error("type must be stream, forum or system.");
+    const role = joinRoleArg(args);
+    if (role === "guest" && args.visibility === "private")
+      throw new Error("join_role guest is for open channels.");
     // Found first, so a wrong name creates nothing.
     const template =
       args.template === undefined
@@ -1396,9 +1409,25 @@ class Tools {
     });
     const shown = await until(() => this.metadata(id), Boolean).catch(unread);
     if (!shown || shown instanceof Error)
-      return `The community accepted channel ${id} but ${shown ? shown.message : "does not show it yet"}${template ? "; the template was not applied" : ""}.`;
+      return `The community accepted channel ${id} but ${shown ? shown.message : "does not show it yet"}${template ? "; the template was not applied" : ""}${role === "guest" ? "; join_role was not set" : ""}.`;
     const lines = [`created ${id}`];
-    if (!template) return lines.join("\n");
+    if (template) lines.push(...(await this.apply(id, template)));
+    // Last, so the template's agents join as members, not guests.
+    if (role === "guest")
+      try {
+        const answer = await this.update(id, { join_role: role });
+        lines.push(
+          answer === `updated ${id}` ? "new people join as guests" : answer,
+        );
+      } catch (error) {
+        lines.push(`join_role not set: ${reason(error)}`);
+      }
+    return lines.join("\n");
+  }
+
+  /** Starts a new channel's Canvas and adds its agents from `template`. */
+  async apply(id: string, template: ChannelTemplate) {
+    const lines: string[] = [];
     // The template's own agents, as Buzz adds them; each is tried.
     const agents = template.agents.filter((key) => key !== this.client.pubkey);
     if (template.canvas.trim())
@@ -1417,10 +1446,10 @@ class Tools {
         lines.push(
           `Canvas not started${agents.length ? ", so no agents were added" : ""}: ${reason(error)}`,
         );
-        return lines.join("\n");
+        return lines;
       }
     if (agents.length) lines.push(...(await this.change(id, agents, [])).lines);
-    return lines.join("\n");
+    return lines;
   }
 
   /** The owner's template named `name`, as one, without guessing. */
@@ -1461,8 +1490,18 @@ class Tools {
     }
     if (args.ttl !== undefined)
       wanted.push(["ttl", String(seconds(args.ttl) ?? "")]);
+    const role = joinRoleArg(args);
+    if (
+      role === "guest" &&
+      (args.visibility ?? (has(metadata, "private") ? "private" : "open")) ===
+        "private"
+    )
+      throw new Error("join_role guest is for open channels.");
+    if (role) wanted.push(["join_role", role]);
     if (!wanted.length)
-      throw new Error("Give name, about, visibility, ttl, topic or purpose.");
+      throw new Error(
+        "Give name, about, visibility, ttl, join_role, topic or purpose.",
+      );
     const value = (key: string) => wanted.find((t) => t[0] === key)?.[1];
     checkDetails(
       value("name"),
@@ -1531,13 +1570,20 @@ class Tools {
     );
     const who = (key: string) =>
       names.has(key) ? `${key} ${names.get(key)}` : key;
+    // With no role asked for, the relay gives a new member the channel's
+    // join_role, which is guest on an announce channel.
+    const shown = (key: string) =>
+      role ??
+      (roster instanceof Error
+        ? undefined
+        : roster.find((m) => m.pubkey === key)?.role);
     const report = (key: string, verb: string, done?: typeof added) =>
       refused.has(key)
         ? `not ${verb} ${who(key)}: ${refused.get(key)}`
         : roster instanceof Error
           ? `${who(key)}: the community accepted it but ${roster.message}`
           : done?.(roster, key)
-            ? `${verb} ${who(key)}${verb === "added" && role ? ` as ${role}` : ""}`
+            ? `${verb} ${who(key)}${verb === "added" && (role || shown(key) !== "member") ? ` as ${shown(key)}` : ""}`
             : `${who(key)}: the community accepted it but does not show it yet`;
     return {
       changed: refused.size < add.length + remove.length,
@@ -2118,6 +2164,15 @@ function seconds(value: unknown) {
   return value;
 }
 
+/** A `join_role` argument: undefined when absent. */
+function joinRoleArg(args: Args) {
+  const value = args.join_role;
+  if (value === undefined) return undefined;
+  if (value !== "member" && value !== "guest")
+    throw new Error("join_role must be member or guest.");
+  return value;
+}
+
 /** A `since` or `before` argument: a Unix time in seconds, inclusive. */
 function unixTime(args: Args, key: string) {
   const value = args[key];