diff --git a/common/arg.cpp b/common/arg.cpp
index 1f70d0ad4..3e63ce0a6 100644
--- a/common/arg.cpp
+++ b/common/arg.cpp
@@ -3646,6 +3646,18 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
             }
         }
     ).set_examples({LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_COMPLETION, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_REASONING"));
+    add_opt(common_arg(
+        {"--reasoning-effort"}, "LEVEL",
+        "reasoning effort level given to the chat template: 'default' to keep the template default,\n"
+        "or a level such as 'minimal', 'low', 'medium', 'high', 'xhigh' or 'max' (default: default)",
+        [](common_params & params, const std::string & value) {
+            if (value == "default") {
+                params.default_template_kwargs.erase("reasoning_effort");
+            } else {
+                params.default_template_kwargs["reasoning_effort"] = json(value).dump();
+            }
+        }
+    ).set_examples({LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_COMPLETION, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_REASONING_EFFORT"));
     add_opt(common_arg(
         {"--reasoning-budget"}, "N",
         "token budget for thinking: -1 for unrestricted, 0 for immediate end, N>0 for token budget (default: -1)",
diff --git a/common/chat.cpp b/common/chat.cpp
index faf51dcd2..a45c51fa0 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -920,6 +920,10 @@ static std::string common_chat_template_direct_apply_impl(
         bool enabled = inp["preserve_reasoning"].get<bool>();
         jinja::caps_apply_preserve_reasoning(ctx, enabled);
     }
+    if (inp.contains("reasoning_effort") && inp["reasoning_effort"].is_string() && !inp["reasoning_effort"].empty()) {
+        std::string reasoning_effort = inp["reasoning_effort"].get<std::string>();
+        jinja::caps_apply_reasoning_effort(ctx, reasoning_effort);
+    }
 
     jinja::global_from_json(ctx, inp, inputs.mark_input);
 
diff --git a/common/jinja/caps.cpp b/common/jinja/caps.cpp
index cdd7ccfa2..fb97909ed 100644
--- a/common/jinja/caps.cpp
+++ b/common/jinja/caps.cpp
@@ -17,7 +17,7 @@ namespace jinja {
 
 using caps_json_fn = std::function<json()>;
 using caps_ctx_fn = std::function<void(context &)>;
-using caps_analyze_fn = std::function<void(bool, value &, value &, const std::string &)>;
+using caps_analyze_fn = std::function<void(context &, bool, value &, value &, const std::string &)>;
 
 void caps_apply_preserve_reasoning(jinja::context & ctx, bool enabled) {
     ctx.set_val("preserve_thinking",         mk_val<value_bool>(enabled));
@@ -26,6 +26,12 @@ void caps_apply_preserve_reasoning(jinja::context & ctx, bool enabled) {
     ctx.set_val("drop_thinking",            mk_val<value_bool>(!enabled));
 }
 
+void caps_apply_reasoning_effort(jinja::context & ctx, const std::string & effort) {
+    value var = mk_val<value_string>(effort); // bind to the same value for stats
+    ctx.set_val("reasoning_effort",   var);
+    ctx.set_val("reasoning_strength", var);
+}
+
 static void caps_try_execute(jinja::program & prog,
                              const caps_json_fn & messages_fn,
                              const caps_ctx_fn & ctx_fn,
@@ -62,7 +68,7 @@ static void caps_try_execute(jinja::program & prog,
         // ignore exceptions during capability analysis
     }
 
-    analyze_fn(success, messages, tools, result);
+    analyze_fn(ctx, success, messages, tools, result);
 }
 
 // for debugging only
@@ -87,6 +93,7 @@ std::map<std::string, bool> caps::to_map() const {
         {"supports_parallel_tool_calls", supports_parallel_tool_calls},
         {"supports_system_role", supports_system_role},
         {"supports_preserve_reasoning", supports_preserve_reasoning},
+        {"supports_reasoning_effort", supports_reasoning_effort},
         {"supports_object_arguments", supports_object_arguments},
     };
 }
@@ -124,7 +131,7 @@ caps caps_get(jinja::program & prog) {
         },
         nullptr, // ctx_fn
         nullptr, // tools_fn
-        [&](bool success, value & messages, value &, const std::string &) {
+        [&](context &, bool success, value & messages, value &, const std::string &) {
             auto & content = messages->at(0)->at("content");
             caps_print_stats(content, "messages[0].content");
             if (has_op(content, "selectattr") || has_op(content, "array_access")) {
@@ -158,7 +165,7 @@ caps caps_get(jinja::program & prog) {
         },
         nullptr, // ctx_fn
         nullptr, // tools_fn
-        [&](bool, value & messages, value &, const std::string &) {
+        [&](context &, bool, value & messages, value &, const std::string &) {
             auto & content = messages->at(0)->at("content");
             caps_print_stats(content, "messages[0].content");
             if (!content->stats.used) {
@@ -234,7 +241,7 @@ caps caps_get(jinja::program & prog) {
                 },
             });
         },
-        [&](bool success, value & messages, value & tools, const std::string &) {
+        [&](context &, bool success, value & messages, value & tools, const std::string &) {
             if (!success) {
                 return; // Nothing can be inferred
             }
@@ -327,7 +334,7 @@ caps caps_get(jinja::program & prog) {
                     },
                 });
             },
-            [&](bool success, value & messages, value & tools, const std::string &) {
+            [&](context &, bool success, value & messages, value & tools, const std::string &) {
                 if (!success) {
                     result.supports_tool_calls = false;
                     result.supports_tools = false;
@@ -429,7 +436,7 @@ caps caps_get(jinja::program & prog) {
                 },
             });
         },
-        [&](bool success, value & messages, value &, const std::string &) {
+        [&](context &, bool success, value & messages, value &, const std::string &) {
             if (!success) {
                 result.supports_parallel_tool_calls = false;
                 return;
@@ -486,7 +493,7 @@ caps caps_get(jinja::program & prog) {
             caps_apply_preserve_reasoning(ctx, true);
         },
         nullptr, // tools_fn
-        [&](bool, value &, value &, const std::string & output) {
+        [&](context &, bool, value &, value &, const std::string & output) {
             // note: we cannot use stats here because the reasoning_content may be used for "if" condition test, but not actually outputted in the final result
             if (output.find(reasoning_placeholder) != std::string::npos) {
                 result.supports_preserve_reasoning = true;
@@ -494,6 +501,32 @@ caps caps_get(jinja::program & prog) {
         }
     );
 
+    JJ_DEBUG("%s\n", ">>> Running capability check: reasoning effort");
+
+    // case: reasoning effort level
+    caps_try_execute(
+        prog,
+        [&]() {
+            // messages
+            return json::array({
+                {
+                    {"role", "user"},
+                    {"content", "User message"}
+                },
+            });
+        },
+        [&](context & ctx) {
+            ctx.set_val("enable_thinking", mk_val<value_bool>(true));
+            caps_apply_reasoning_effort(ctx, "low");
+        },
+        nullptr, // tools_fn
+        [&](context & ctx, bool, value &, value &, const std::string &) {
+            value effort = ctx.get_val("reasoning_effort");
+            caps_print_stats(effort, "reasoning_effort");
+            result.supports_reasoning_effort = effort->stats.used;
+        }
+    );
+
     JJ_DEBUG("%s\n", result.to_string().c_str());
 
     return result;
diff --git a/common/jinja/caps.h b/common/jinja/caps.h
index a290cd7da..b81dd95f2 100644
--- a/common/jinja/caps.h
+++ b/common/jinja/caps.h
@@ -16,6 +16,9 @@ struct caps {
     // supports preserve reasoning trace in the full history, not just the last assistant message
     bool supports_preserve_reasoning = false;
 
+    // supports reasoning effort levels
+    bool supports_reasoning_effort = false;
+
     // one of the 2 content capabilities must be true
     bool supports_string_content = true;
     bool supports_typed_content = false;
@@ -32,5 +35,6 @@ struct caps {
 caps caps_get(jinja::program & prog);
 
 void caps_apply_preserve_reasoning(jinja::context & ctx, bool enabled);
+void caps_apply_reasoning_effort(jinja::context & ctx, const std::string & effort);
 
 } // namespace jinja
diff --git a/tests/test-chat.cpp b/tests/test-chat.cpp
index de75ad330..51ad85484 100644
--- a/tests/test-chat.cpp
+++ b/tests/test-chat.cpp
@@ -6955,6 +6955,24 @@ static void test_reasoning_budget_message_per_request() {
     }
 }
 
+static void test_reasoning_effort_caps() {
+    LOG_DBG("%s\n", __func__);
+
+    auto assert_supports_effort = [](const std::string & path, bool expected) {
+        auto tmpls = read_templates(path);
+        assert_equals(expected, common_chat_templates_get_caps(tmpls.get()).at("supports_reasoning_effort"));
+    };
+
+    assert_supports_effort("models/templates/deepseek-ai-DeepSeek-V4.jinja", true);
+    assert_supports_effort("models/templates/muse-glimmer.jinja", true);
+    assert_supports_effort("models/templates/tencent-Hy3.jinja", true);
+    assert_supports_effort("models/templates/openai-gpt-oss-120b.jinja", true);
+    assert_supports_effort("models/templates/upstage-Solar-Open-100B.jinja", true);
+    assert_supports_effort("models/templates/Cohere2MoE.jinja", true);
+    assert_supports_effort("models/templates/meta-llama-Llama-3.1-8B-Instruct.jinja", false);
+    assert_supports_effort("models/templates/Qwen-Qwen3-0.6B.jinja", false);
+}
+
 static void test_msg_diffs_compute() {
     LOG_DBG("%s\n", __func__);
     {
@@ -7114,6 +7132,7 @@ int main(int argc, char ** argv) {
         test_deepseek_v4_thinking_retention();
         test_deepseek_v4_tool_result_ordering();
         test_template_generation_prompt();
+        test_reasoning_effort_caps();
         test_reasoning_budget_tokens_per_request();
         test_reasoning_budget_message_per_request();
         test_template_output_peg_parsers(detailed_debug);
diff --git a/tools/cli/README.md b/tools/cli/README.md
index 880c4a540..b3543ed4d 100644
--- a/tools/cli/README.md
+++ b/tools/cli/README.md
@@ -170,6 +170,7 @@
 | `--jinja, --no-jinja` | whether to use jinja template engine for chat (default: enabled)<br/>(env: LLAMA_ARG_JINJA) |
 | `--reasoning-format FORMAT` | controls whether thought tags are allowed and/or extracted from the response, and in which format they're returned; one of:<br/>- none: leaves thoughts unparsed in `message.content`<br/>- deepseek: puts thoughts in `message.reasoning_content`<br/>- deepseek-legacy: keeps `<think>` tags in `message.content` while also populating `message.reasoning_content`<br/>(default: auto)<br/>(env: LLAMA_ARG_THINK) |
 | `-rea, --reasoning [on\|off\|auto]` | Use reasoning/thinking in the chat ('on', 'off', or 'auto', default: 'auto' (detect from template))<br/>(env: LLAMA_ARG_REASONING) |
+| `--reasoning-effort LEVEL` | reasoning effort level given to the chat template: 'default' to keep the template default,<br/>or a level such as 'minimal', 'low', 'medium', 'high', 'xhigh' or 'max' (default: default)<br/>(env: LLAMA_ARG_REASONING_EFFORT) |
 | `--reasoning-budget N` | token budget for thinking: -1 for unrestricted, 0 for immediate end, N>0 for token budget (default: -1)<br/>(env: LLAMA_ARG_THINK_BUDGET) |
 | `--reasoning-budget-message MESSAGE` | message injected before the end-of-thinking tag when reasoning budget is exhausted (default: none)<br/>(env: LLAMA_ARG_THINK_BUDGET_MESSAGE) |
 | `--reasoning-preserve, --no-reasoning-preserve` | preserve reasoning trace in the full history, not just the last assistant message (default: template default)<br/>compatible with certain templates having 'supports_preserve_reasoning' capability<br/>example: https://docs.z.ai/guides/capabilities/thinking-mode#preserved-thinking<br/>(env: LLAMA_ARG_REASONING_PRESERVE) |
diff --git a/tools/completion/README.md b/tools/completion/README.md
index c2e52ac06..3bc2d823e 100644
--- a/tools/completion/README.md
+++ b/tools/completion/README.md
@@ -251,6 +251,7 @@ llama-completion.exe -m models\gemma-1.1-7b-it.Q4_K_M.gguf --ignore-eos -n -1
 | `--jinja, --no-jinja` | whether to use jinja template engine for chat (default: disabled)<br/>(env: LLAMA_ARG_JINJA) |
 | `--reasoning-format FORMAT` | controls whether thought tags are allowed and/or extracted from the response, and in which format they're returned; one of:<br/>- none: leaves thoughts unparsed in `message.content`<br/>- deepseek: puts thoughts in `message.reasoning_content`<br/>- deepseek-legacy: keeps `<think>` tags in `message.content` while also populating `message.reasoning_content`<br/>(default: auto)<br/>(env: LLAMA_ARG_THINK) |
 | `-rea, --reasoning [on\|off\|auto]` | Use reasoning/thinking in the chat ('on', 'off', or 'auto', default: 'auto' (detect from template))<br/>(env: LLAMA_ARG_REASONING) |
+| `--reasoning-effort LEVEL` | reasoning effort level given to the chat template: 'default' to keep the template default,<br/>or a level such as 'minimal', 'low', 'medium', 'high', 'xhigh' or 'max' (default: default)<br/>(env: LLAMA_ARG_REASONING_EFFORT) |
 | `--reasoning-budget N` | token budget for thinking: -1 for unrestricted, 0 for immediate end, N>0 for token budget (default: -1)<br/>(env: LLAMA_ARG_THINK_BUDGET) |
 | `--reasoning-budget-message MESSAGE` | message injected before the end-of-thinking tag when reasoning budget is exhausted (default: none)<br/>(env: LLAMA_ARG_THINK_BUDGET_MESSAGE) |
 | `--reasoning-preserve, --no-reasoning-preserve` | preserve reasoning trace in the full history, not just the last assistant message (default: template default)<br/>compatible with certain templates having 'supports_preserve_reasoning' capability<br/>example: https://docs.z.ai/guides/capabilities/thinking-mode#preserved-thinking<br/>(env: LLAMA_ARG_REASONING_PRESERVE) |
diff --git a/tools/server/README.md b/tools/server/README.md
index a2ab872b4..ec3a33e0c 100644
--- a/tools/server/README.md
+++ b/tools/server/README.md
@@ -226,6 +226,7 @@ For the full list of features, please refer to [server's changelog](https://gith
 | `--jinja, --no-jinja` | whether to use jinja template engine for chat (default: enabled)<br/>(env: LLAMA_ARG_JINJA) |
 | `--reasoning-format FORMAT` | controls whether thought tags are allowed and/or extracted from the response, and in which format they're returned; one of:<br/>- none: leaves thoughts unparsed in `message.content`<br/>- deepseek: puts thoughts in `message.reasoning_content`<br/>- deepseek-legacy: keeps `<think>` tags in `message.content` while also populating `message.reasoning_content`<br/>(default: auto)<br/>(env: LLAMA_ARG_THINK) |
 | `-rea, --reasoning [on\|off\|auto]` | Use reasoning/thinking in the chat ('on', 'off', or 'auto', default: 'auto' (detect from template))<br/>(env: LLAMA_ARG_REASONING) |
+| `--reasoning-effort LEVEL` | reasoning effort level given to the chat template: 'default' to keep the template default,<br/>or a level such as 'minimal', 'low', 'medium', 'high', 'xhigh' or 'max' (default: default)<br/>(env: LLAMA_ARG_REASONING_EFFORT) |
 | `--reasoning-budget N` | token budget for thinking: -1 for unrestricted, 0 for immediate end, N>0 for token budget (default: -1)<br/>(env: LLAMA_ARG_THINK_BUDGET) |
 | `--reasoning-budget-message MESSAGE` | message injected before the end-of-thinking tag when reasoning budget is exhausted (default: none)<br/>(env: LLAMA_ARG_THINK_BUDGET_MESSAGE) |
 | `--reasoning-preserve, --no-reasoning-preserve` | preserve reasoning trace in the full history, not just the last assistant message (default: template default)<br/>compatible with certain templates having 'supports_preserve_reasoning' capability<br/>example: https://docs.z.ai/guides/capabilities/thinking-mode#preserved-thinking<br/>(env: LLAMA_ARG_REASONING_PRESERVE) |
@@ -1250,7 +1251,7 @@ The `response_format` parameter supports both plain JSON output (e.g. `{"type":
 
 `chat_template_kwargs`: Allows sending additional parameters to the json templating system. For example: `{"enable_thinking": false}`
 
-`reasoning_effort`: If set to `none`, reasoning will be disabled for this request. Other values (e.g., `low`, `max`) have no effect on reasoning.
+`reasoning_effort`: If `none`, reasoning/thinking is disabled. Otherwise, the value is made available to the jinja template.
 
 `reasoning_format`: The reasoning format to be parsed. If set to `none`, it will output the raw generated text.
 
diff --git a/tools/server/server-common.cpp b/tools/server/server-common.cpp
index 5ff7685bb..7ed486528 100644
--- a/tools/server/server-common.cpp
+++ b/tools/server/server-common.cpp
@@ -1292,12 +1292,15 @@ json oaicompat_chat_params_parse(
         throw std::invalid_argument("invalid type for \"enable_thinking\" (expected boolean, got string)");
     }
 
-    // Parse also the OAI "reasoning_effort": "none" specific value
+    // Parse the OAI "reasoning_effort" field; "none" disables reasoning.
     if (body.contains("reasoning_effort")) {
         auto reasoning_effort = json_value(body, "reasoning_effort", std::string(""));
         if (reasoning_effort == "none") {
             inputs.enable_thinking = false;
-        } // other reasoning_effort values are model-specific and not yet handled
+            inputs.chat_template_kwargs.erase("reasoning_effort");
+        } else if (!reasoning_effort.empty()) {
+            inputs.chat_template_kwargs["reasoning_effort"] = json(reasoning_effort).dump();
+        }
     }
 
     inputs.force_pure_content = opt.force_pure_content;