> For clean Markdown of any page, append `.md` to the page URL. > For a complete documentation index, see https://docs.sarvam.ai/llms.txt. > For full documentation content in one file, see https://docs.sarvam.ai/llms-full.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.sarvam.ai/_mcp/server. # GLM-5.3 > GLM-5.3 is an open-source model served on Sarvam infrastructure. 1,048,576 token context window with tool calling and visible reasoning. GLM-5.3 is an [open-source model](/api/getting-started/models/open-source) served by Sarvam in **beta**, and is **not tuned for Indian languages**. Beta access is granted per API key — [contact us](/api/getting-started/help) to request whitelisting. For Indian language workloads use [Sarvam-105B](/api/getting-started/models/sarvam-105b) instead. A general-purpose open-source model. Its distinguishing feature on Sarvam is a very large **1,048,576 token context window** — eight times the 128K offered by Sarvam's own chat models — which makes it a reasonable choice for reasoning over long documents or large codebases in a single request. ## At a Glance | | | | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Model ID** | `glm5.3` | | **What it does** | General-purpose chat LLM; very long context and tool calling | | **Languages** | Not tuned for Indian languages by Sarvam | | **APIs** | [`POST /v2/chat/completions`](/api-reference/open-source/chat-completions) and [`POST /v2/responses`](/api-reference/open-source/responses) — also see [using an open-source model](/api/getting-started/models/open-source#using-an-open-source-model) | | **Input limits** | 1,048,576-token context window; 10 MB request cap — [all limits](#limits-and-errors) | | **Benchmarks** | None published by Sarvam | | **Pricing** | ₹126 input · ₹23.4 cached input · ₹396 output — per 1M tokens; reasoning billed as output ([Pricing](/api/getting-started/pricing)) | | **Best for** | Long-document and large-codebase analysis in a single request | | **Not for** | Indian language workloads — use [Sarvam-105B](/api/getting-started/models/sarvam-105b) | ## Why you might use it #### Very long context A 1,048,576 token context window lets you pass entire books, long transcripts, or large code repositories in one request without chunking or retrieval. #### Tool calling Supports the OpenAI-compatible `tools` and `tool_choice` parameters, so it works with agentic loops and function-calling frameworks. ## Model Specifications #### Key Considerations * Model ID: `glm5.3` * Context window: 1,048,576 tokens (1M) * Tool calling: supported * Image input: **not supported** — text only * Reasoning: **always on** — chat: `reasoning_content` (counts against `max_tokens`); Responses: a reasoning item with `summary[]` by default. `extra_body` thinking switch is accepted but does not currently disable it * Maximum request size: 10 MB * Temperature range: 0 to 2 (unset uses the model's own default) * Top-p range: greater than 0, up to 1 (`0` currently returns `503`) * Supports streaming and non-streaming on both routes * OpenAI-compatible chat completions and Responses protocols ## GLM-5.3 vs Sarvam's chat model | Feature | GLM-5.3 | Sarvam-105B | | -------------------------- | ----------------------- | --------------------------------------------- | | **Context window** | 1,048,576 | 128,000 | | **Tool calling** | ✅ | ✅ | | **Image input** | ❌ | ❌ | | **Indian language tuning** | None | 23 languages | | **Best for** | Very long-context tasks | Maximum quality reasoning & agentic workflows | Pick GLM-5.3 **only** when your task genuinely needs more than 128K of context. For everything else — and especially for anything touching Indian languages — a Sarvam model will serve you better and comes with Sarvam's own evaluation behind it. ## Key Capabilities #### Basic Chat Completion A single-turn request. Only the `model` field differs from a Sarvam chat completion call. #### Python ```python from sarvamai import SarvamAI client = SarvamAI(api_subscription_key="YOUR_SARVAM_API_KEY") response = client.open_source_models.chat_completions_v2( model="glm5.3", messages=[ {"role": "user", "content": "Explain the difference between a B-tree and a B+ tree index."} ], temperature=0.2, top_p=1, max_tokens=2000, ) print(response.choices[0].message.content) ``` #### JavaScript ```javascript import { SarvamAIClient } from "sarvamai"; const client = new SarvamAIClient({ apiSubscriptionKey: "YOUR_SARVAM_API_KEY", }); async function main() { const response = await client.openSourceModels.chatCompletionsV2({ model: "glm5.3", messages: [ { role: "user", content: "Explain the difference between a B-tree and a B+ tree index.", }, ], temperature: 0.2, top_p: 1, max_tokens: 2000, }); console.log(response.choices[0].message.content); } main(); ``` #### cURL ```bash curl -X POST https://api.sarvam.ai/v2/chat/completions \ -H "api-subscription-key: $SARVAM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "messages": [ {"role": "user", "content": "Explain the difference between a B-tree and a B+ tree index."} ], "model": "glm5.3", "temperature": 0.2, "top_p": 1, "max_tokens": 2000 }' ``` The answer is in `message.content`. The model's chain-of-thought arrives separately in `message.reasoning_content` — see [Reasoning](#reasoning) below for how to budget for it or turn it off. #### Long-Context Analysis GLM-5.3's main advantage. Pass a large document directly in the prompt instead of chunking it — up to 1,048,576 tokens of context, minus whatever you reserve for `max_tokens`. #### Python ```python from sarvamai import SarvamAI client = SarvamAI(api_subscription_key="YOUR_SARVAM_API_KEY") with open("annual_report.txt", encoding="utf-8") as f: document = f.read() response = client.open_source_models.chat_completions_v2( model="glm5.3", messages=[ {"role": "system", "content": "You are a financial analyst. Answer only from the document provided."}, {"role": "user", "content": f"{document}\n\nList every material risk disclosed, with the page or section it appears in."}, ], temperature=0.1, max_tokens=4000, ) print(response.choices[0].message.content) ``` #### cURL ```bash # Build the payload with a file so large documents do not hit shell argument limits. python3 - <<'PY' > payload.json import json document = open("annual_report.txt", encoding="utf-8").read() json.dump({ "model": "glm5.3", "messages": [ {"role": "system", "content": "You are a financial analyst. Answer only from the document provided."}, {"role": "user", "content": document + "\n\nList every material risk disclosed."}, ], "temperature": 0.1, "max_tokens": 4000, }, open("payload.json", "w")) PY curl -X POST https://api.sarvam.ai/v2/chat/completions \ -H "api-subscription-key: $SARVAM_API_KEY" \ -H "Content-Type: application/json" \ --data-binary @payload.json ``` Requests are capped at **10 MB** regardless of the context window. A document that fits in 1,048,576 tokens can still exceed the byte cap and return `413 Payload Too Large`. #### Tool Calling GLM-5.3 supports OpenAI-compatible function calling. #### Python ```python from sarvamai import SarvamAI client = SarvamAI(api_subscription_key="YOUR_SARVAM_API_KEY") response = client.open_source_models.chat_completions_v2( model="glm5.3", messages=[ {"role": "user", "content": "What is the weather in Bengaluru right now?"} ], tools=[ { "type": "function", "function": { "name": "get_weather", "description": "Get the current weather for a city.", "parameters": { "type": "object", "properties": { "city": {"type": "string", "description": "City name"} }, "required": ["city"], }, }, } ], tool_choice="auto", max_tokens=1000, ) print(response.choices[0].message.tool_calls) ``` #### cURL ```bash curl -X POST https://api.sarvam.ai/v2/chat/completions \ -H "api-subscription-key: $SARVAM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "glm5.3", "messages": [ {"role": "user", "content": "What is the weather in Bengaluru right now?"} ], "tools": [ { "type": "function", "function": { "name": "get_weather", "description": "Get the current weather for a city.", "parameters": { "type": "object", "properties": {"city": {"type": "string"}}, "required": ["city"] } } } ], "tool_choice": "auto", "max_tokens": 1000 }' ``` #### Streaming Set `stream` to `true` to receive tokens as server-sent events. Because GLM-5.3 reasons before answering, the stream delivers `delta.reasoning_content` chunks first and `delta.content` chunks after — read both, or the wait before the first `content` chunk looks like a stall. #### Python ```python from sarvamai import SarvamAI client = SarvamAI(api_subscription_key="YOUR_SARVAM_API_KEY") stream = client.open_source_models.chat_completions_v2( model="glm5.3", messages=[ {"role": "user", "content": "Write a short note on database normalisation."} ], max_tokens=1000, stream=True, ) for chunk in stream: delta = chunk.choices[0].delta reasoning = getattr(delta, "reasoning_content", None) if reasoning: pass # the chain-of-thought — show it, log it, or skip it if delta.content: print(delta.content, end="", flush=True) ``` #### cURL ```bash curl -N -X POST https://api.sarvam.ai/v2/chat/completions \ -H "api-subscription-key: $SARVAM_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "glm5.3", "messages": [ {"role": "user", "content": "Write a short note on database normalisation."} ], "max_tokens": 1000, "stream": true }' ``` With `stream: true`, pass top-level `stream_options: {"include_usage": true}` to receive a later chunk with `usage`, including `completion_tokens_details.reasoning_tokens`. Putting `stream_options` inside `extra_body` is `400`. Chat still ends with `[DONE]`. ## Reasoning GLM-5.3 thinks before every answer — **by default**, not only when `reasoning_effort` is set. **Chat.** The chain-of-thought arrives in `message.reasoning_content` (`delta.reasoning_content` when streaming); `content` carries only the final answer. Reasoning tokens are billed, count against `max_tokens`, and are reported on `usage.completion_tokens_details.reasoning_tokens`. A small budget can be consumed entirely by reasoning, returning `content: null` with `finish_reason: "length"`. **Responses.** A reasoning item is returned by default, with text in `summary[]`. `reasoning.summary` is optional (`auto` / `detailed`). `reasoning.effort` accepts `none`, `minimal`, `low`, `medium`, `high`, `xhigh` — **`max` is `400`** on this route. Usage is on `output_tokens_details.reasoning_tokens`. Hitting `max_output_tokens` reports `status: "incomplete"` with `incomplete_details.reason: max_output_tokens`. `extra_body.chat_template_kwargs.enable_thinking: false` is accepted on chat but **does not currently disable GLM-5.3 thinking**. Use `reasoning_effort: "low"` to keep the trace short, or raise `max_tokens` / `max_output_tokens`. Structured JSON is reliable on [`POST /v2/responses`](/api-reference/open-source/responses) with `text.format` `json_object` or strict `json_schema` — that path skips the reasoning item. ## Parameters Chat accepts the OpenAI-compatible set plus GLM sampling fields that the [full parameter table](/api/getting-started/models/open-source#supported-parameters) lists: `temperature`, `top_p`, `top_k` (`null` / `-1` / `≥ 1`; `0` is `400`), `min_p` (`0`–`1`), `repetition_penalty` (`> 0` and `≤ 2`), `max_tokens`, `stream`, `stream_options`, `stop`, `n`, `seed`, `frequency_penalty`, `presence_penalty`, `reasoning_effort` (`none` / `minimal` / `low` / `medium` / `high` / `xhigh` / `max`), `response_format`, `tools`, `tool_choice`, `parallel_tool_calls`, and `extra_body`. Message roles include `developer` as well as `system` / `user` / `assistant` / `tool`. Responses (`POST /v2/responses`) is create-only and stateless: replay `input` every turn. Omit `store` or pass `false` (OpenAI SDKs default `true` — that call is `400`). Named extras: `instructions` (echoed), `top_p`, `text.format` (`text` / `json_object` / `json_schema`; `format` required whenever you send `text`), `reasoning.effort` / `reasoning.summary`, `parallel_tool_calls`. `presence_penalty` and `frequency_penalty` are echoed as `0` on this route and should not be treated as honoured. Model-specific exceptions: * **`image_url` content parts are rejected** (`400`) — GLM-5.3 is text only. * **`seed` is not currently reproducible** on this model — identical seeds return different completions. Use `temperature: 0` where you need stability. * **An assistant message as the last chat turn is a prior turn**, not token-level prefill — the model restarts rather than continuing the supplied suffix. ## Limits and errors Common errors for every model on `/v2/chat/completions` are documented on the [Open-Source Models overview](/api/getting-started/models/open-source#errors). GLM-5.3-specific cases: | Condition | Status | Code | What it means | | -------------------------------------------------------------------------- | ------ | ---------------------------- | --------------------------------------------------------------------------------------------------------------------------- | | API key lacks beta access | `400` | `invalid_request_error` | Request whitelisting — see [Beta APIs](/api-reference/beta-apis). | | Missing or invalid API key | `403` | `invalid_api_key_error` | Check the `api-subscription-key` header. | | No credits remaining | `402` | `insufficient_quota_error` | Top up on the [dashboard](https://dashboard.sarvam.ai). | | Unknown or unavailable model id | `404` | `not_found_error` | Confirm the id with [`GET /v2/models`](/api-reference/open-source/models). | | Message contains an image part | `400` | `invalid_request_error` | GLM-5.3 is text only. Use [`gemma4`](/api/getting-started/models/open-source/gemma-4-31b) for image input. | | `max_tokens` above 1,048,576 | `400` | `invalid_request_error` | `max_tokens` cannot exceed the context window. | | Estimated prompt tokens + `max_tokens` above 1,048,576 | `422` | `unprocessable_entity_error` | Shorten the prompt or lower `max_tokens`. | | Request body above the model's size cap | `413` | `invalid_request_error` | The byte cap is independent of the token window. | | `tool_choice` naming a function with no `tools` | `422` | `unprocessable_entity_error` | Provide the `tools` array alongside `tool_choice`. | | Invalid tool schema (`$ref`, recursion, size) | `400` | `invalid_request_error` | See [Tool schemas](/api/getting-started/models/open-source#tool-schemas). | | Rate limit exceeded | `429` | `rate_limit_exceeded_error` | Back off and retry; see [Rate Limits](/api/getting-started/ratelimits). | | Model overloaded after retries | `503` | `model_overloaded` | Retry later. | | `content: null` with `finish_reason: "length"` | `200` | — | Reasoning consumed the whole `max_tokens` budget — raise it, or set `reasoning_effort: "low"`. See [Reasoning](#reasoning). | | `content: null` with `finish_reason: "stop"` and `response_format` set | `200` | — | Reasoning ate the JSON budget — raise `max_tokens`, or use Responses `text.format`. See [Reasoning](#reasoning). | | Chat `top_k: 0` / `min_p` out of `0–1` / `repetition_penalty` `0` or `> 2` | `400` | `invalid_request_error` | See [supported parameters](/api/getting-started/models/open-source#supported-parameters). | | Responses `reasoning.effort: "max"` | `400` | `invalid_request_error` | Use `none` / `minimal` / `low` / `medium` / `high` / `xhigh`. | | `top_p: 0` | `503` | `model_overloaded` | Must be greater than 0. Current serving fails this as 503, not 400. | ## Support Sarvam supports the serving layer — auth, billing, rate limits, availability. Sarvam does not tune or evaluate this model, so its output quality, reasoning, and language coverage are properties of the model itself. See [Open-Source Models](/api/getting-started/models/open-source) for the full support boundary, and [Talk to us](/api/getting-started/help) for serving issues.