diff --git a/src/familiar/planets.py b/src/familiar/planets.py
new file mode 100644
index 0000000..d5dff39
--- /dev/null
+++ b/src/familiar/planets.py
@@ -0,0 +1,62 @@
+"""Read-only planetary interaction tools.
+
+Despite the ``manage_planets`` scope name, ESI exposes only *reads* for PI, so
+these tools list colonies and their layouts; there is no PI write endpoint.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from fastmcp import FastMCP
+
+from . import auth
+from .charutil import run_per_character, run_per_corp, summarize
+from .esi import client
+
+
+async def get_planets(character: str | int | None = None, limit: int = 20) -> dict[str, Any]:
+    """Planetary colonies for one character or all (planet, type, upgrade level)."""
+
+    async def fetch(token: str, cid: int) -> dict[str, Any]:
+        colonies = await client().get(f"/characters/{cid}/planets/", token=token) or []
+        return summarize(colonies, limit)
+
+    return await run_per_character(character, fetch)
+
+
+async def get_planet_layout(character: str | int, planet_id: int) -> dict[str, Any]:
+    """Full layout (pins, links, routes) of one colony for a character."""
+    cid = auth.resolve_character(character)
+    token, _ = await auth.get_auth(cid)
+    data = await client().get(f"/characters/{cid}/planets/{planet_id}/", token=token) or {}
+    return {
+        "character_id": cid,
+        "planet_id": planet_id,
+        "pins": len(data.get("pins") or []),
+        "links": len(data.get("links") or []),
+        "routes": len(data.get("routes") or []),
+    }
+
+
+async def get_corp_customs_offices(
+    character: str | int | None = None, limit: int = 20
+) -> dict[str, Any]:
+    """Corp customs offices (POCOs) — needs a corp role — for one corp or all."""
+
+    async def fetch(token: str, corp_id: int, cid: int) -> dict[str, Any]:
+        offices = await client().get_all_pages(
+            f"/corporations/{corp_id}/customs_offices/", token=token
+        )
+        return summarize(offices, limit)
+
+    return await run_per_corp(character, fetch)
+
+
+TOOLS = [get_planets, get_planet_layout, get_corp_customs_offices]
+
+
+def register(mcp: FastMCP) -> None:
+    """Register the planetary interaction tools onto the given server."""
+    for fn in TOOLS:
+        mcp.tool(fn)
diff --git a/src/familiar/server.py b/src/familiar/server.py
index f6e66ef..5a6d3a1 100644
--- a/src/familiar/server.py
+++ b/src/familiar/server.py
@@ -24,6 +24,7 @@ from . import (
     killmails,
     market,
     misc,
+    planets,
     profile,
     structures,
     trade,
@@ -99,3 +100,6 @@ fittings.register(mcp)
 # Phase 4: fleet (read + guarded writes) and UI commands (guarded writes).
 fleet.register(mcp)
 ui.register(mcp)
+
+# Phase 4: planetary interaction (read-only).
+planets.register(mcp)
diff --git a/tests/test_planets.py b/tests/test_planets.py
new file mode 100644
index 0000000..5dfea56
--- /dev/null
+++ b/tests/test_planets.py
@@ -0,0 +1,53 @@
+"""Planetary interaction read tools."""
+
+import asyncio
+
+import pytest
+
+from conftest import route
+from familiar import auth, planets
+from familiar.server import mcp
+
+CHARS = [{"character_id": 99, "character_name": "Alpha", "scopes": []}]
+
+
+@pytest.fixture
+def fake_auth(monkeypatch):
+    monkeypatch.setattr(auth, "list_characters", lambda: list(CHARS))
+
+    async def get_auth(cid, **kw):
+        return f"token-{cid}", cid
+
+    monkeypatch.setattr(auth, "get_auth", get_auth)
+    monkeypatch.setattr(auth, "resolve_character", lambda i: 99)
+    return CHARS
+
+
+def test_get_planets(mock_esi, fake_auth):
+    cols = [{"planet_id": 40000001, "planet_type": "barren", "upgrade_level": 3}]
+    mock_esi(lambda r: route(r, {"/planets/": cols}))
+    res = asyncio.run(planets.get_planets())
+    assert res["characters"][0]["count"] == 1
+
+
+def test_get_planet_layout(mock_esi, fake_auth):
+    layout = {"pins": [{}, {}], "links": [{}], "routes": [{}, {}, {}]}
+    mock_esi(lambda r: route(r, {"/planets/40000001/": layout}))
+    res = asyncio.run(planets.get_planet_layout(99, 40000001))
+    assert res["pins"] == 2
+    assert res["routes"] == 3
+
+
+def test_corp_customs_offices(mock_esi, fake_auth):
+    fixtures = {
+        "/customs_offices/": [{"office_id": 1}],
+        "/characters/": {"corporation_id": 2000},
+    }
+    mock_esi(lambda r: route(r, fixtures))
+    res = asyncio.run(planets.get_corp_customs_offices())
+    assert res["characters"][0]["count"] == 1
+
+
+def test_planets_tools_registered():
+    tools = {t.name for t in asyncio.run(mcp.list_tools())}
+    assert {"get_planets", "get_planet_layout", "get_corp_customs_offices"} <= tools