Scene initialized (OPTIX GPU, AgX Punchy, Blender 4.x sky). Now I'll generate the terrain with an analytically carved pond, shoreline sand, path, and pads — baking mask data into a vertex color attribute for shading.

import bpy, math
from mathutils import Vector
from mathutils import noise as bnoise

scene = bpy.context.scene
info = {}

def sm(a,b,x):
    if abs(a-b) < 1e-9: return 0.0
    t = min(max((x-a)/(b-a), 0.0), 1.0)
    return t*t*(3-2*t)

C = Vector((-7.5, 3.0))
R = 10.4
ZW = -0.18   # water level

def reff(a):
    return R*(1.0 + 0.16*math.cos(3*a+math.pi) + 0.09*math.sin(2*a))

def fbm(x, y, s=0.0):
    v=0.0; a=1.0; f=0.055
    p = Vector((x*f, y*f, 7.31+s))
    for i in range(4):
        v += a*bnoise.noise(p)
        a *= 0.5; p *= 2.13
    return v

pads = [(6.8,-4.6,4.6,0.62), (1.6,-1.9,2.0,0.40)]

path_pts = [(6.8,-7.2),(5.4,-5.6),(3.2,-3.4),(1.6,-1.9)]
segs = []
total_len = 0.0
for i in range(len(path_pts)-1):
    ax,ay = path_pts[i]; bx,by = path_pts[i+1]
    L = math.hypot(bx-ax, by-ay)
    segs.append((ax,ay,bx,by,L,total_len))
    total_len += L

def path_eval(x,y):
    best = (1e9, 0.0)
    for ax,ay,bx,by,L,acc in segs:
        abx,aby = bx-ax, by-ay
        apx,apy = x-ax, y-ay
        L2 = L*L
        t = 0.0 if L2 == 0 else min(max((apx*abx+apy*aby)/L2, 0.0), 1.0)
        px,py = ax+t*abx, ay+t*aby
        d = math.hypot(x-px, y-py)
        if d < best[0]:
            best = (d, min(max((acc + t*L)/max(total_len,1e-6),0.0),1.0))
    return best

def height_masks(x, y):
    n = fbm(x,y)
    h = 0.55*n
    h += 2.3*math.exp(-(((x+13)**2 + (y-17)**2))/(288.0))     # NW ridge
    h += 1.5*math.exp(-(((x-20)**2 + (y-1)**2))/(200.0))      # E hills
    h += 0.9*sm(22,34, math.hypot(x,y))                        # rim rise
    dx,dy = x-C.x, y-C.y
    d = math.hypot(dx,dy); a = math.atan2(dy,dx)
    fm = sm(R*0.70, R*1.22, d)
    h *= (0.12 + 0.88*fm)
    pad_t = 0.0
    for cx,cy,rad,tg in pads:
        pd = math.hypot(x-cx, y-cy)
        t = sm(rad, rad*0.55, pd)
        if t > 0:
            pad_t = max(pad_t, t)
            tgt = tg + 0.10*fbm(x*1.6+9, y*1.6, 3.0)
            h = h*(1-t) + tgt*t
    dp, tt = path_eval(x,y)
    tp = sm(2.0, 0.8, dp)
    if tp > 0:
        tgt = 0.62 + (0.40-0.62)*tt + 0.05*fbm(x*2.0, y*2.0, 5.0)
        h = h*(1-tp) + tgt*tp
    rr = 9.9
    ins = 0.0
    if d < R*1.35:
        rr = d/max(reff(a), 0.001)
        ins = sm(1.06, 0.42, rr)
        if ins > 0:
            bed = -1.55 + 0.07*bnoise.noise(Vector((x*0.7, y*0.7, 2.2)))
            h = h*(1-ins) + bed*ins
            h += 0.05*fbm(x*1.3, y*1.3, 8.0)*ins
    # masks
    shore_band = max(0.0, sm(1.34,1.06,rr) - sm(0.94,0.82,rr)) if d < R*1.4 else 0.0
    sand = shore_band * sm(ZW-0.50, ZW-0.02, h)
    sed  = sm(ZW-0.02, ZW-0.40, h) if d < R*1.3 else 0.0
    gv = 0.5+0.5*bnoise.noise(Vector((x*0.35, y*0.35, 1.7)))
    return h, min(tp,1.0), min(sand,1.0), min(sed,1.0), gv

# ---- build grid ----
bpy.ops.mesh.primitive_grid_add(x_subdivisions=280, y_subdivisions=280,
                                size=64, location=(0,0,0), calc_uvs=True)
ter = bpy.context.active_object
ter.name = "Ground"
me = ter.data

vs = me.vertices
n_v = len(vs)
print("verts:", n_v)

import numpy as np
H = np.zeros(n_v, dtype=np.float32)
DIRT = np.zeros(n_v, dtype=np.float32)
SAND = np.zeros(n_v, dtype=np.float32)
SED  = np.zeros(n_v, dtype=np.float32)
GV   = np.zeros(n_v, dtype=np.float32)

co = np.empty(n_v*3, dtype=np.float32)
vs.foreach_get("co", co)
xs = co[0::3]; ys = co[1::3]

for i in range(n_v):
    h, dt_, sd_, se_, gv_ = height_masks(float(xs[i]), float(ys[i]))
    H[i]=h; DIRT[i]=dt_; SAND[i]=sd_; SED[i]=se_; GV[i]=gv_

co[2::3] = H
vs.foreach_set("co", co)

# color attribute POINT/FLOAT_COLOR with 4 channels
ca = me.color_attributes.new(name="mask", type='FLOAT_COLOR', domain='POINT')
data = np.empty(n_v*4, dtype=np.float32)
data[0::4] = DIRT; data[1::4] = GV; data[2::4] = SAND; data[3::4] = SED
ca.data.foreach_set("color", data)

me.update()

# smooth normals
import bmesh
bm = bmesh.new(); bm.from_mesh(me)
bmesh.ops.smooth_vertex(bm, verts=bm.verts, factor=0.6)
bm.to_mesh(me); bm.free()

for p in me.polygons: p.use_smooth = True
me.shade_smooth()

# collections
def link_to(obj, cname):
    col = bpy.data.collections.get(cname)
    if col is None:
        col = bpy.data.collections.new(cname); scene.collection.children.link(col)
    for c in list(obj.users_collection): c.objects.unlink(obj)
    col.objects.link(obj)
link_to(ter, "Terrain")

# ---------- terrain material ----------
mat = bpy.data.materials.new("GroundMat"); mat.use_nodes = True
nt = mat.node_tree; nt.nodes.clear()
out = nt.nodes.new("ShaderNodeOutputMaterial"); out.location=(600,0)
bsdf = nt.nodes.new("ShaderNodeBsdfPrincipled")
nt.links.new(bsdf.outputs['BSDF'], out.inputs['Surface'])
attr = nt.nodes.new("ShaderNodeAttribute"); attr.attribute_name="mask"; attr.location=(-500,100)
sep = nt.nodes.new("ShaderNodeSeparateColor"); sep.location=(-320,100)
nt.links.new(attr.outputs['Color'], sep.inputs['Color'])
mix = nt.nodes.new("ShaderNodeMixRGB"); mix.blend_type='MIX'; mix.location=(-100,150)
grass_a=(0.088,0.135,0.045,1); grass_b=(0.205,0.235,0.075,1)
mix.inputs['Color1'].default_value=grass_a
mix.inputs['Color2'].default_value=grass_b
nt.links.new(sep.outputs['Green'], mix.inputs['Fac'])
sand_c=(0.44,0.365,0.245,1)
m2 = nt.nodes.new("ShaderNodeMixRGB"); m2.blend_type='MIX'; m2.location=(80,150)
m2.inputs['Color1'].default_value=(0,0,0,1); m2.inputs['Color2'].default_value=sand_c
nt.links.new(mix.outputs['Color'], m2.inputs['Color1'])
nt.links.new(sep.outputs['Blue'], m2.inputs['Fac'])
dirt_c=(0.185,0.125,0.075,1)
m3 = nt.nodes.new("ShaderNodeMixRGB"); m3.blend_type='MIX'; m3.location=(260,150)
m3.inputs['Color2'].default_value=dirt_c
nt.links.new(m2.outputs['Color'], m3.inputs['Color1'])
nt.links.new(sep.outputs['Red'], m3.inputs['Fac'])
sed_c=(0.075,0.072,0.055,1)
m4 = nt.nodes.new("ShaderNodeMixRGB"); m4.blend_type='MIX'; m4.location=(420,150)
m4.inputs['Color2'].default_value=sed_c
nt.links.new(m3.outputs['Color'], m4.inputs['Color1'])
nt.links.new(sep.outputs['Alpha'], m4.inputs['Fac'])
nt.links.new(m4.outputs['Color'], bsdf.inputs['Base Color'])
# macro variation + bump
texco = nt.nodes.new("ShaderNodeTexCoord"); texco.location=(-500,-250)
noiz = nt.nodes.new("ShaderNodeTexNoise"); noiz.location=(-320,-250)
noiz.inputs['Scale'].default_value=0.35; noiz.inputs['Detail'].default_value=6
rampv = nt.nodes.new("ShaderNodeMapRange"); rampv.location=(-140,-250)
rampv.inputs['From Min'].default_value=0.35; rampv.inputs['From Max'].default_value=0.72
rampv.inputs['To Min'].default_value=0.72; rampv.inputs['To Max'].default_value=0.95
nt.links.new(texco.outputs['Object'], noiz.inputs['Vector'])
nt.links.new(noiz.outputs['Fac'], rampv.inputs['Value'])
nt.links.new(rampv.outputs['Result'], bsdf.inputs['Roughness'])
bumpn = nt.nodes.new("ShaderNodeTexNoise"); bumpn.location=(-320,-480)
bumpn.inputs['Scale'].default_value=2.2; bumpn.inputs['Detail'].default_value=8
bmp = nt.nodes.new("ShaderNodeBump"); bmp.location=(80,-480)
bmp.inputs['Strength'].default_value=0.22; bmp.inputs['Distance'].default_value=0.03
nt.links.new(texco.outputs['Object'], bumpn.inputs['Vector'])
nt.links.new(bumpn.outputs['Fac'], bmp.inputs['Height'])
nt.links.new(bmp.outputs['Normal'], bsdf.inputs['Normal'])
ter.data.materials.append(mat)

info["terrain_verts"] = n_v
info["height_range"] = [float(H.min()), float(H.max())]
result = info


Traceback (most recent call last):
  File "<repo>\.runner\blender-mcp-v1.0.0\addon\mcp_to_blender_server.py", line 230, in _execute_code
    exec(code, namespace)
    ~~~~^^^^^^^^^^^^^^^^^
  File "<string>", line 131, in <module>
AttributeError: BMeshOpsModule: operator "smooth_vertex" doesn't exist. Did you mean: 'smooth_vert'?