> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tess.im/llms.txt
> Use this file to discover all available pages before exploring further.

# GLM 5.3

GLM 5.3 (Zhipu AI / Z.ai) is the **text-only flagship** for **complex software engineering** and **long-horizon agents** in Tess. Same 1M context as GLM 5.2 — stronger reasoning, always on, with native tools.

| **Model ID**<br /><br />`glm-5.3`                                       | **Context**<br /><br />1M   | **Provider**<br /><br />Zhipu AI (Z.ai) | **Released**<br /><br />18 Aug 2026      |
| :---------------------------------------------------------------------- | :-------------------------- | :-------------------------------------- | :--------------------------------------- |
| **Capabilities**<br /><br /><Icon icon="brain" /><Icon icon="wrench" /> | **Speed**<br /><br />Medium | **Cost**<br /><br />Medium–High         | **Intelligence**<br /><br />Text-to-text |

## What changed vs GLM 5.2

|                           | GLM 5.2                         | GLM 5.3                                            |
| ------------------------- | ------------------------------- | -------------------------------------------------- |
| Focus                     | Long-horizon open-source coding | Software engineering + persistent agents           |
| Context                   | 1M                              | 1M                                                 |
| Reasoning                 | On/off (Thinking)               | **Always on** — low / high / **max** (default max) |
| Vision                    | No                              | No                                                 |
| Tools                     | Yes                             | Yes                                                |
| Tess credits / 100 tokens | 0.067 in / 0.211 out            | **0.192 in / 0.603 out**                           |

Native **reasoning** and **tools** (function calling / MCP). **No vision** — for screenshots, UI, or video, use **GLM 5.3 Flash** (`glm-5.3-flash`) in the same catalog.

## Pricing (Tess credits)

Values follow [Models and Costs](/en/models-and-cost) (credits per 100 tokens):

| Model   | Input / 100 tokens | Output / 100 tokens | Cache read / 100 tokens |
| ------- | ------------------ | ------------------- | ----------------------- |
| GLM 5.3 | 0.192              | 0.603               | 0.036                   |

GLM 5.3 costs about **3× GLM 5.2**. Cached context reads are billed below a full input pass — keep long threads on the same model to take advantage of that.

> **Screenshot placeholder — model picker:** Capture the chat model selector with **GLM 5.3** selected.

## Ideal use cases in Tess

1. Long-horizon software engineering — multi-file refactors, debugging, implementation on a large codebase
2. Persistent agents — planning, tool loops, and multi-step execution without dropping the thread
3. Deep reasoning by default — tasks that must think before the final answer
4. Text-only workflows when vision is not needed
5. 1M-context sessions without switching models

<Tip>
  **Best practices**

  * Reasoning **cannot be turned off**. Every turn spends reasoning tokens — even on **low**. Do not use GLM 5.3 as a cheap extractor.
  * Start on **high**; reserve **max** for planning-heavy or long tool loops.
  * Prefer **GLM 5.2** (`glm-5.2`) when you need the same 1M context at lower cost and can live with lighter reasoning.
  * Prefer **GLM 5.3 Flash** when the job includes images or video, or when you want Flash-priced agents with similar agentic quality.
  * Lean on context cache in long chats to keep input cost down.
</Tip>

See also: [GLM 5.2](/en/glm-5-2) · [Models and Costs](/en/models-and-cost) · [GLM 5.3 (OpenRouter)](https://openrouter.ai/z-ai/glm-5.3).