diff --git a/core/http/endpoints/openai/list_capabilities.go b/core/http/endpoints/openai/list_capabilities.go
index 72a645ef6..27583385a 100644
--- a/core/http/endpoints/openai/list_capabilities.go
+++ b/core/http/endpoints/openai/list_capabilities.go
@@ -36,6 +36,12 @@ func ListModelCapabilitiesEndpoint(bcl *config.ModelConfigLoader, ml *model.Mode
 		for _, m := range modelNames {
 			entry := schema.ModelCapabilities{ID: m, Object: "model"}
 			if cfg, ok := modelConfigFor(bcl, m); ok {
+				// Mirror the request path: SetDefaults applies the application
+				// default only when the model leaves context_size unset. An
+				// explicit 0 or -1 falls through to the backend fallback there.
+				if cfg.ContextSize == nil && appConfig != nil && appConfig.ContextSize > 0 {
+					cfg.ContextSize = &appConfig.ContextSize
+				}
 				entry.Capabilities = cfg.Capabilities()
 				entry.ThreeDOperations = cfg.ThreeDOperations()
 				entry.InputModalities = cfg.InputModalities()
diff --git a/core/http/endpoints/openai/list_capabilities_test.go b/core/http/endpoints/openai/list_capabilities_test.go
index 0c8a5d4ff..ecfc85f81 100644
--- a/core/http/endpoints/openai/list_capabilities_test.go
+++ b/core/http/endpoints/openai/list_capabilities_test.go
@@ -160,6 +160,33 @@ parameters:
 		Expect(entry).NotTo(BeNil())
 		Expect(entry.ContextSize).To(Equal(backend.DefaultContextSize))
 	})
+
+	It("uses application config context size when model context_size is unset", func() {
+		writeConfig("llm-app-default", `
+name: llm-app-default
+backend: llama-cpp
+parameters:
+  model: model.gguf
+`)
+		appConf.ContextSize = 8192
+		entry := entryFor(call(), "llm-app-default")
+		Expect(entry).NotTo(BeNil())
+		Expect(entry.ContextSize).To(Equal(8192))
+	})
+
+	It("keeps the backend fallback when the model sets a non-positive context_size", func() {
+		writeConfig("llm-explicit-zero", `
+name: llm-explicit-zero
+backend: llama-cpp
+context_size: 0
+parameters:
+  model: model.gguf
+`)
+		appConf.ContextSize = 8192
+		entry := entryFor(call(), "llm-explicit-zero")
+		Expect(entry).NotTo(BeNil())
+		Expect(entry.ContextSize).To(Equal(backend.DefaultContextSize))
+	})
 	It("reports an alias with its target's capabilities and context_size", func() {
 		writeConfig("real-llm", `
 name: real-llm
diff --git a/docs/content/features/api-discovery.md b/docs/content/features/api-discovery.md
index f45524423..932634a39 100644
--- a/docs/content/features/api-discovery.md
+++ b/docs/content/features/api-discovery.md
@@ -141,6 +141,11 @@ curl http://localhost:8080/api/instructions/config-management?format=json
 
 An additive, LocalAI-specific superset of `/v1/models`. It returns the same set of models but enriches each entry with the **capabilities** the model supports and the **input/output modalities** it accepts and produces. Use it to decide, before sending a request, whether a given model can take an image, audio, or video attachment directly - or whether the input needs converting/transcribing first.
 
+The reported `context_size` uses a positive model-level value first.
+If the model does not set `context_size`, it uses **Settings → Performance → Default Context Size** when positive.
+Otherwise, it uses the backend fallback of 4096 tokens.
+For llama.cpp with separate KV caches, the reported value accounts for the number of parallel slots.
+
 Because it is purely additive, clients that only understand `/v1/models` keep working unchanged; they simply never call this route.
 
 ```bash