diff --git a/controllers/api/mcp_view.go b/controllers/api/mcp_view.go
new file mode 100644
index 0000000..4df915d
--- /dev/null
+++ b/controllers/api/mcp_view.go
@@ -0,0 +1,20 @@
+package api
+
+import (
+	"net/http"
+)
+
+// viaMCP reports whether r is an MCP tool call.
+func viaMCP(r *http.Request) bool { return false }
+
+// includeBody reports whether r asks for the material body.
+func includeBody(r *http.Request) bool { return false }
+
+// materialView is the answer of GET /materials/{id} for r.
+func materialView(r *http.Request, d materialDetailJSON) any { return d }
+
+// managedMaterialView is a managed material for r.
+func managedMaterialView(r *http.Request, m managedMaterialJSON, write bool) any { return m }
+
+// managedMaterialDetailView is a managed material with its files for r.
+func managedMaterialDetailView(r *http.Request, d managedMaterialDetailJSON, write bool) any { return d }
diff --git a/controllers/api/mcp_view_test.go b/controllers/api/mcp_view_test.go
new file mode 100644
index 0000000..46872cf
--- /dev/null
+++ b/controllers/api/mcp_view_test.go
@@ -0,0 +1,166 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/bouncer"
+)
+
+// mcpRequest is a request as pier dispatches it in-process: the api_token
+// marker with a principal on its context.
+func mcpRequest(method, target string) *http.Request {
+	r := httptest.NewRequest(method, target, nil)
+	return r.WithContext(bouncer.WithDispatch(r.Context(), &bouncer.Dispatch{
+		Guards:    []string{"api_token"},
+		Principal: &bouncer.Principal{ID: 7},
+	}))
+}
+
+// keysOf marshals v and returns its top-level JSON object.
+func keysOf(t *testing.T, v any) map[string]any {
+	t.Helper()
+	raw, err := json.Marshal(v)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var out map[string]any
+	if err := json.Unmarshal(raw, &out); err != nil {
+		t.Fatal(err)
+	}
+	return out
+}
+
+func TestViaMCP(t *testing.T) {
+	plain := httptest.NewRequest(http.MethodGet, "/", nil)
+	if viaMCP(plain) {
+		t.Error("a plain request is an MCP call")
+	}
+	if !viaMCP(mcpRequest(http.MethodGet, "/")) {
+		t.Error("a dispatched api_token request is not an MCP call")
+	}
+	backend := httptest.NewRequest(http.MethodGet, "/", nil)
+	backend = backend.WithContext(bouncer.WithDispatch(backend.Context(), &bouncer.Dispatch{
+		Guards:    []string{"backend"},
+		Principal: &bouncer.Principal{ID: 7},
+	}))
+	if viaMCP(backend) {
+		t.Error("a backend dispatch is an MCP call of jz.bm")
+	}
+	for target, want := range map[string]bool{
+		"/":                    false,
+		"/?include_body=false": false,
+		"/?include_body=0":     false,
+		"/?include_body=true":  true,
+		"/?include_body=1":     true,
+	} {
+		if got := includeBody(httptest.NewRequest(http.MethodGet, target, nil)); got != want {
+			t.Errorf("includeBody(%s) = %v, want %v", target, got, want)
+		}
+	}
+}
+
+func TestMCPMaterialView(t *testing.T) {
+	body := "transcript text"
+	url := "https://x.test/a"
+	detail := materialDetailJSON{
+		materialListJSON: materialListJSON{ID: 3, Title: "T", Type: "notatka", URL: &url, Tags: []tagJSON{}},
+		Body:             &body,
+		Files:            []fileJSON{{ID: 9, URL: "/storage/f.pdf", Name: "f.pdf", Size: 10, Mime: "application/pdf"}},
+	}
+
+	t.Run("plain request unchanged", func(t *testing.T) {
+		got := keysOf(t, materialView(httptest.NewRequest(http.MethodGet, "/", nil), detail))
+		want := keysOf(t, detail)
+		gotRaw, _ := json.Marshal(got)
+		wantRaw, _ := json.Marshal(want)
+		if string(gotRaw) != string(wantRaw) {
+			t.Errorf("plain view = %s, want %s", gotRaw, wantRaw)
+		}
+	})
+
+	t.Run("MCP without include_body", func(t *testing.T) {
+		got := keysOf(t, materialView(mcpRequest(http.MethodGet, "/"), detail))
+		if _, ok := got["body"]; ok {
+			t.Errorf("body present: %v", got)
+		}
+		if got["body_omitted"] != true {
+			t.Errorf("body_omitted = %v, want true", got["body_omitted"])
+		}
+		files, _ := got["files"].([]any)
+		if len(files) != 1 {
+			t.Fatalf("files = %v", got["files"])
+		}
+		f := files[0].(map[string]any)
+		for _, k := range []string{"id", "name", "size", "mime", "url"} {
+			if _, ok := f[k]; !ok {
+				t.Errorf("file lacks %s: %v", k, f)
+			}
+		}
+		if got["title"] != "T" || got["url"] != url {
+			t.Errorf("list fields lost: %v", got)
+		}
+	})
+
+	t.Run("MCP without include_body, empty body", func(t *testing.T) {
+		empty := detail
+		empty.Body = nil
+		got := keysOf(t, materialView(mcpRequest(http.MethodGet, "/"), empty))
+		if _, ok := got["body"]; ok {
+			t.Errorf("body present: %v", got)
+		}
+		if _, ok := got["body_omitted"]; ok {
+			t.Errorf("body_omitted set for an empty body: %v", got)
+		}
+	})
+
+	t.Run("MCP with include_body", func(t *testing.T) {
+		got := keysOf(t, materialView(mcpRequest(http.MethodGet, "/?include_body=true"), detail))
+		if got["body"] != body {
+			t.Errorf("body = %v, want %q", got["body"], body)
+		}
+		if _, ok := got["body_omitted"]; ok {
+			t.Errorf("body_omitted set with include_body: %v", got)
+		}
+	})
+
+	managed := managedMaterialJSON{ID: 3, Title: "T", Type: "notatka", Body: &body, Tags: []tagJSON{}}
+
+	t.Run("managed plain unchanged", func(t *testing.T) {
+		got := keysOf(t, managedMaterialView(httptest.NewRequest(http.MethodGet, "/", nil), managed, false))
+		if got["body"] != body {
+			t.Errorf("plain managed body = %v", got["body"])
+		}
+		if _, ok := got["body_omitted"]; ok {
+			t.Errorf("plain managed has body_omitted: %v", got)
+		}
+	})
+
+	t.Run("managed MCP read", func(t *testing.T) {
+		got := keysOf(t, managedMaterialView(mcpRequest(http.MethodGet, "/"), managed, false))
+		if _, ok := got["body"]; ok || got["body_omitted"] != true {
+			t.Errorf("managed MCP read = %v, want no body and body_omitted", got)
+		}
+		got = keysOf(t, managedMaterialView(mcpRequest(http.MethodGet, "/?include_body=1"), managed, false))
+		if got["body"] != body {
+			t.Errorf("managed MCP read with include_body = %v", got)
+		}
+	})
+
+	t.Run("managed MCP write never echoes the body", func(t *testing.T) {
+		got := keysOf(t, managedMaterialView(mcpRequest(http.MethodPost, "/?include_body=true"), managed, true))
+		if _, ok := got["body"]; ok || got["body_omitted"] != true {
+			t.Errorf("managed MCP write = %v, want no body and body_omitted", got)
+		}
+		d := managedMaterialDetailJSON{managedMaterialJSON: managed, Files: []fileJSON{}}
+		got = keysOf(t, managedMaterialDetailView(mcpRequest(http.MethodPost, "/?include_body=true"), d, true))
+		if _, ok := got["body"]; ok || got["body_omitted"] != true {
+			t.Errorf("managed MCP write detail = %v, want no body and body_omitted", got)
+		}
+		if _, ok := got["files"]; !ok {
+			t.Errorf("managed MCP write detail lost files: %v", got)
+		}
+	})
+}
diff --git a/mcp_links.go b/mcp_links.go
new file mode 100644
index 0000000..ff52fb3
--- /dev/null
+++ b/mcp_links.go
@@ -0,0 +1,9 @@
+package bm
+
+import "net/http"
+
+// MiddlewareMCPLinks makes the links of an MCP answer absolute.
+const MiddlewareMCPLinks = "jz.bm.mcp-links"
+
+// mcpLinks is not implemented yet.
+func (p *Plugin) mcpLinks(next http.Handler) http.Handler { return next }
diff --git a/mcp_test.go b/mcp_test.go
index fafdba1..28679ec 100644
--- a/mcp_test.go
+++ b/mcp_test.go
@@ -1,13 +1,19 @@
 package bm_test
 
 import (
+	"bytes"
+	"context"
+	"encoding/json"
 	"net/http"
+	"net/http/httptest"
 	"reflect"
 	"slices"
+	"strconv"
 	"strings"
 	"testing"
 
 	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/bouncer"
 	"git.golem15.com/golem15/summercms/modules/pact"
 	"git.golem15.com/golem15/summercms/modules/pier"
 	"git.golem15.com/golem15/summercms/modules/surf"
@@ -47,6 +53,8 @@ var pinnedTools = []string{
 	"bm_deadlines",
 	"bm_mark_reading_owned",
 	"bm_mark_reading_read",
+	"bm_material",
+	"bm_materials",
 	"bm_meetings",
 	"bm_readings",
 	"bm_schedule",
@@ -63,6 +71,8 @@ var studentQueryKeys = map[string][]string{
 	"schedule":  {"from", "to"},
 	"deadlines": {"from", "to"},
 	"readings":  {"course"},
+	"materials": {"course", "meeting", "tag", "type", "page", "per_page"},
+	"material":  {"include_body"},
 }
 
 // bmTools returns jz.bm's declared tools.
@@ -240,3 +250,137 @@ func TestTokenMirrorRoutes(t *testing.T) {
 		}
 	}
 }
+
+// dispatched returns r as pier dispatches it in-process: the api_token
+// marker with principal id on its context.
+func dispatched(r *http.Request, id uint) *http.Request {
+	return r.WithContext(bouncer.WithDispatch(r.Context(), &bouncer.Dispatch{
+		Guards:    []string{"api_token"},
+		Principal: &bouncer.Principal{ID: id},
+	}))
+}
+
+// TestMCPLinks (D-16): under MCP every string under url or *_url that starts
+// with a single / becomes absolute; other keys, protocol-relative and
+// absolute URLs, error answers and plain HTTP answers are left alone.
+func TestMCPLinks(t *testing.T) {
+	const answer = `{"data":{"url":"/storage/x","files":[{"url":"/storage/y","name":"/n"}],"syllabus_url":"/sylabusy/z.pdf","link":"https://x.test/a","other":"/keep","cdn_url":"//cdn.test/a","abs_url":"https://y.test/b","count":12345678901234567890,"nested":{"items":[{"thumb_url":"/t.png"}]}}}`
+	mw := (&bm.Plugin{}).Middlewares()[bm.MiddlewareMCPLinks]
+	if mw == nil {
+		t.Fatalf("%s is not exported", bm.MiddlewareMCPLinks)
+	}
+	handler := func(status int, body string) http.Handler {
+		return mw(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Length", strconv.Itoa(len(body)))
+			w.WriteHeader(status)
+			_, _ = w.Write([]byte(body))
+		}))
+	}
+
+	t.Run("plain HTTP untouched", func(t *testing.T) {
+		rec := httptest.NewRecorder()
+		handler(http.StatusOK, answer).ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))
+		if rec.Body.String() != answer {
+			t.Errorf("plain answer = %s, want it unchanged", rec.Body.String())
+		}
+	})
+
+	t.Run("MCP answer absolute", func(t *testing.T) {
+		rec := httptest.NewRecorder()
+		handler(http.StatusOK, answer).ServeHTTP(rec, dispatched(httptest.NewRequest(http.MethodGet, "/", nil), 7))
+		if rec.Code != http.StatusOK {
+			t.Fatalf("status = %d", rec.Code)
+		}
+		if cl := rec.Header().Get("Content-Length"); cl != strconv.Itoa(rec.Body.Len()) {
+			t.Errorf("Content-Length = %s, body is %d bytes", cl, rec.Body.Len())
+		}
+		dec := json.NewDecoder(bytes.NewReader(rec.Body.Bytes()))
+		dec.UseNumber()
+		var got struct {
+			Data map[string]any `json:"data"`
+		}
+		if err := dec.Decode(&got); err != nil {
+			t.Fatalf("decode %s: %v", rec.Body.String(), err)
+		}
+		d := got.Data
+		want := map[string]string{
+			"url":          "http://example.com/storage/x",
+			"syllabus_url": "http://example.com/sylabusy/z.pdf",
+			"link":         "https://x.test/a",
+			"other":        "/keep",
+			"cdn_url":      "//cdn.test/a",
+			"abs_url":      "https://y.test/b",
+		}
+		for k, v := range want {
+			if d[k] != v {
+				t.Errorf("%s = %v, want %s", k, d[k], v)
+			}
+		}
+		file := d["files"].([]any)[0].(map[string]any)
+		if file["url"] != "http://example.com/storage/y" || file["name"] != "/n" {
+			t.Errorf("files[0] = %v", file)
+		}
+		thumb := d["nested"].(map[string]any)["items"].([]any)[0].(map[string]any)
+		if thumb["thumb_url"] != "http://example.com/t.png" {
+			t.Errorf("nested thumb_url = %v", thumb["thumb_url"])
+		}
+		if n, _ := d["count"].(json.Number); n.String() != "12345678901234567890" {
+			t.Errorf("count = %v, want the number kept exactly", d["count"])
+		}
+	})
+
+	t.Run("MCP forwarded scheme", func(t *testing.T) {
+		rec := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		r.Host = "bm.example.test"
+		r.Header.Set("X-Forwarded-Proto", "https")
+		handler(http.StatusOK, `{"url":"/a"}`).ServeHTTP(rec, dispatched(r, 7))
+		if !strings.Contains(rec.Body.String(), `"https://bm.example.test/a"`) {
+			t.Errorf("answer = %s", rec.Body.String())
+		}
+	})
+
+	t.Run("MCP error untouched", func(t *testing.T) {
+		const notFound = `{"error":"not_found","url":"/x"}`
+		rec := httptest.NewRecorder()
+		handler(http.StatusNotFound, notFound).ServeHTTP(rec, dispatched(httptest.NewRequest(http.MethodGet, "/", nil), 7))
+		if rec.Code != http.StatusNotFound || rec.Body.String() != notFound {
+			t.Errorf("error answer = %d %s", rec.Code, rec.Body.String())
+		}
+	})
+}
+
+// TestManageBucketKey (research Pitfall 6): a dispatched management call is
+// throttled per user, a bearer request per token hash, a bare one per IP;
+// the token twins are throttled per user.
+func TestManageBucketKey(t *testing.T) {
+	buckets := (&bm.Plugin{}).Buckets()
+	manage, ok := buckets["jz.bm.manage"]
+	if !ok {
+		t.Fatal("jz.bm.manage is not declared")
+	}
+	if manage.Max != 120 {
+		t.Errorf("jz.bm.manage Max = %d, want 120", manage.Max)
+	}
+	if got := manage.Key(dispatched(httptest.NewRequest(http.MethodGet, "/", nil), 7)); got != "jz.bm.manage.user|7" {
+		t.Errorf("dispatched key = %q, want jz.bm.manage.user|7", got)
+	}
+	bearer := httptest.NewRequest(http.MethodGet, "/", nil)
+	bearer.Header.Set("Authorization", "Bearer usr_secret")
+	if got := manage.Key(bearer); !strings.HasPrefix(got, "jz.bm.manage.token|") || strings.Contains(got, "usr_secret") {
+		t.Errorf("bearer key = %q, want the token hash", got)
+	}
+	if got := manage.Key(httptest.NewRequest(http.MethodGet, "/", nil)); !strings.HasPrefix(got, "jz.bm.manage.ip|") {
+		t.Errorf("bare key = %q, want the IP", got)
+	}
+	token, ok := buckets["jz.bm.token"]
+	if !ok {
+		t.Fatal("jz.bm.token is not declared")
+	}
+	r := httptest.NewRequest(http.MethodGet, "/", nil)
+	r = r.WithContext(bouncer.WithUser(context.Background(), &bouncer.Principal{ID: 7}))
+	if got := token.Key(r); got != "jz.bm.token|u:7" {
+		t.Errorf("token twin key = %q, want jz.bm.token|u:7", got)
+	}
+}
diff --git a/realtime_access.go b/realtime_access.go
index d934edf..c74f8bc 100644
--- a/realtime_access.go
+++ b/realtime_access.go
@@ -20,9 +20,12 @@ const MiddlewareRealtimeAccess = "jz.bm.realtime-access"
 // here without importing that plugin.
 const presentationsOwnerGuard = "presentations.realtime-owner"
 
-// Middlewares exports the realtime access guard.
+// Middlewares exports the realtime access guard and the MCP link rewriter.
 func (p *Plugin) Middlewares() map[string]pact.Middleware {
-	return map[string]pact.Middleware{MiddlewareRealtimeAccess: p.realtimeAccess}
+	return map[string]pact.Middleware{
+		MiddlewareRealtimeAccess: p.realtimeAccess,
+		MiddlewareMCPLinks:       p.mcpLinks,
+	}
 }
 
 // realtimeAccess lets a chat-group member through, otherwise, when