[Feature]: Add native bedrock/zai.glm-5 support with tool calling #24993

Feature Request

Add zai.glm-5 (GLM 5 by Z.AI/Zhipu AI) to the Bedrock model registry so it can be used as bedrock/zai.glm-5 with full tool-use support.

Current Behavior

• bedrock/zai.glm-5 fails with NotFoundError: Unknown provider=None, model=zai.glm-5
• The suggested workaround bedrock/converse/zai.glm-5 works for basic chat but raises UnsupportedParamsError when tools are passed
• This makes GLM 5 unusable for agentic workflows (OpenCode, Claude Code, etc.) that require function calling

Expected Behavior

bedrock/zai.glm-5 should work like other Bedrock models (bedrock/deepseek.v3.2, bedrock/zai.glm-4.7) — supporting streaming, tool calling, and message format transformation.

Evidence

GLM 5 is available on Bedrock in eu-west-2 (and other regions) since March 18, 2026. Direct boto3 calls work fine:

import boto3, json
client = boto3.client('bedrock-runtime', region_name='eu-west-2')
r = client.invoke_model(
    modelId='zai.glm-5',
    body=json.dumps({'messages': [{'role': 'user', 'content': 'hi'}], 'max_tokens': 5}),
    contentType='application/json'
)
print(json.loads(r['body'].read()))
# OK: {'choices': [{'message': {'content': "Hello! I'm GL", 'role': 'assistant'}}], ...}

The model supports tools natively — it's only the LiteLLM routing layer that's missing the registry entry.

Environment

• LiteLLM version: 1.83.0
• AWS region: eu-west-2
• Model ID on Bedrock: zai.glm-5
• Related: [Feature]: Add zai provider #23327 (dashboard UI), [Bug]: Bedrock Tool calling broken: role: "tool" not transformed to Bedrock toolResult format #21087 (tool calling transformation)

Motivation

GLM 5 scores 30/30 tasks 5/5 on SWE-Bench (highly consistent), has 200K context and 128K output window, making it one of the strongest open-weight coding models on Bedrock. Without native support in LiteLLM, it can't be used in tool-calling workflows.