docs(agent): name the fallback row cap and the empty tuning field

Author: mzxchandra

apps/docs/content/docs/workflows/blocks/agent.mdx

@@ -87,7 +87,7 @@ Some settings live under advanced, or appear only for models that support them:
 - **Reasoning effort / Thinking level.** For models with extended reasoning, how much the model thinks before answering. Higher is more thorough but slower and costs more tokens.
 - **Prompt caching.** For Anthropic Claude models, reuses the system prompt and tool definitions between runs instead of re-reading them every time. Cached input costs a tenth of the normal rate, but writing the cache costs 1.25x, so leave it off for one-off runs and turn it on when the same agent runs repeatedly. The cache covers a prefix only if it reaches 1,024 tokens (2,048 on Haiku) — below that Anthropic ignores it and nothing changes. Entries expire after five minutes of no use.
 - **API key.** Your key for the chosen provider. Hidden on hosted Sim, which supplies one.
-- **Fallback models.** An ordered list of models to try when the request to the selected model fails, whether the provider is overloaded, rate-limited, or down. Sim tries the 2nd choice, then the 3rd, and so on, once each, and `<agent.model>` reports the model that answered. Hosted models need no setup. A model that needs its own key takes it from a workspace environment variable you pick on the row; a model on the same provider as the selected model reuses the block's key. Azure, Bedrock, and Vertex models can only be fallbacks for a selected model of the same family, since they use that model's credentials. The Auto model cannot be a fallback. A fallback runs with the selected model's settings where its provider accepts them: temperature and max output tokens are clamped to the fallback's limits, and when the fallback has a reasoning effort, thinking level, or verbosity setting that the selected model's value does not fit, the row shows that field so you can pick a value for it, otherwise the provider's default applies.
+- **Fallback models.** An ordered list of up to five models to try when the request to the selected model fails, whether the provider is overloaded, rate-limited, or down. Sim tries the 2nd choice, then the 3rd, and so on, once each, and `<agent.model>` reports the model that answered. Hosted models need no setup. A model that needs its own key takes it from a workspace environment variable you pick on the row; a model on the same provider as the selected model reuses the block's key. Azure, Bedrock, and Vertex models can only be fallbacks for a selected model of the same family, since they use that model's credentials. The Auto model cannot be a fallback. A fallback runs with the selected model's settings where its provider accepts them: temperature and max output tokens are clamped to the fallback's limits, and when the fallback has a reasoning effort, thinking level, or verbosity setting that the selected model's value does not fit, the row shows that field so you can pick a value for it; leave it empty and the provider's default applies.
 - **Retry on fail.** Retries the selected model after a failure, up to a maximum number of tries with a wait between them. When its tries run out, the fallback models are tried in order, once each, with no wait before the first of them. A fallback is never retried. A failure that happens after the model already called a tool runs that conversation again on the next try or the next model, so keep fallbacks and retry off for agents whose tools must not repeat.
 
 OpenAI and Gemini cache automatically at no extra cost and need no setting; their discount is already reflected in what you are charged.