# Talking while waiting (/en/ai/platform/build/shape-the-conversation/filler-words) > For AI agents: see the complete documentation index at [llms.txt](/llms.txt). > Documentation: Conversational AI. > Documentation version: Preview. > This document describes only this version. [Version index](/llms/doc-versions-convoai-guides-v2.txt). In conversational AI, delays in LLM responses may cause users to wonder if the agent is still processing, repeat their question, or disengage entirely. Filler words address this by playing short phrases while the agent waits for the LLM to generate a response. Common use cases for filler words include: - **Tool calls**: When the agent calls tools, response times can increase significantly. Filler words bridge this gap while the agent waits for tool results. - **Complex queries**: Queries that require more LLM processing time benefit from a brief acknowledgment to signal that the agent is working on a response. - **Customer service scenarios**: In support interactions, filler words such as "Let me look into that for you" reassure users that their request is being handled. ## Understand the tech You configure filler words on the agent. When the LLM hasn't responded within a wait threshold, the agent plays a filler word. The filler word comes from one of the following sources: - **Static**: The agent picks a phrase from a list you provide. - **Generated**: Agora generates a short phrase that fits the conversation, based on instructions you provide. If a generated phrase isn't ready in time, the agent falls back to a static phrase. Generated mode requires the agent's LLM to use your own provider key with OpenAI, Groq, or xAI. Playing a filler word doesn't cancel or restart the LLM request. The agent continues with its reply once the LLM responds. The agent plays at most one filler word per turn, and if the LLM responds before the wait threshold, the agent doesn't play a filler word. ## Prerequisites Before you begin, make sure that you have created an agent and started a session as described in [Create an agent and start a session](/en/ai/platform/get-started/start-stop-agent). ## Configure static filler words Configure filler words when you [create](/en/api-reference/api-ref/conversational-ai/platform/create-agent) or [update](/en/api-reference/api-ref/conversational-ai/platform/update-agent) the agent. In the following example, the agent plays a phrase from the list when the LLM hasn't responded within 1.5 seconds. The SDK examples start from the `agent` builder in [Create an agent](/en/ai/platform/get-started/start-stop-agent#create-an-agent). **Python SDK** Set the wait time in `fixed_time_config`, and the phrases and selection rule in `static_config`: ```python filler_agent = agent.with_filler_words( { "enable": True, "trigger": { "mode": "fixed_time", "fixed_time_config": {"response_wait_ms": 1500}, }, "content": { "mode": "static", "static_config": { "phrases": [ "Please wait.", "Okay.", "Uh-huh.", "Let me look into that.", "One moment.", ], "selection_rule": "shuffle", }, }, } ) ``` **TypeScript SDK** Set the wait time in `fixed_time_config`, and the phrases and selection rule in `static_config`: ```ts const fillerAgent = agent.withFillerWords({ enable: true, trigger: { mode: 'fixed_time', fixed_time_config: { response_wait_ms: 1500 }, }, content: { mode: 'static', static_config: { phrases: [ 'Please wait.', 'Okay.', 'Uh-huh.', 'Let me look into that.', 'One moment.', ], selection_rule: 'shuffle', }, }, }); ``` **Go SDK** Set the wait time in `FixedTimeConfig`, and the phrases and selection rule in `StaticConfig`. The Go examples on this page also import the SDK's root package as `Agora "github.com/AgoraIO/agora-agents-go/v2"`. ```go fillerAgent := agent.WithFillerWords(&agentkit.FillerWordsConfig{ Enable: Agora.Bool(true), Trigger: &agentkit.FillerWordsTrigger{ Mode: Agora.String("fixed_time"), FixedTimeConfig: &agentkit.FillerWordsTriggerFixedTimeConfig{ ResponseWaitMs: Agora.Int(1500), }, }, Content: &agentkit.FillerWordsContent{ Mode: agentkit.FillerWordsContentModeStatic.Ptr(), StaticConfig: &agentkit.FillerWordsContentStaticConfig{ Phrases: []string{ "Please wait.", "Okay.", "Uh-huh.", "Let me look into that.", "One moment.", }, SelectionRule: agentkit.FillerWordsSelectionRuleShuffle.Ptr(), }, }, }) ``` **REST API** Add a `filler_words` object to the agent configuration, at the same level as `instructions` and `pipeline`: ```json "filler_words": { "enable": true, "trigger": { "mode": "fixed_time", "response_wait_ms": 1500 }, "content": { "mode": "static", "phrases": [ "Please wait.", "Okay.", "Uh-huh.", "Let me look into that.", "One moment." ], "selection_rule": "shuffle" } } ``` | Field | Description | | -------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- | | `enable` | Whether to play filler words. | | `trigger.mode` | When to play a filler word. Set to `fixed_time`. | | `trigger.response_wait_ms` | How long in milliseconds to wait for the LLM before playing a filler word, from `100` to `10000`. Required. | | `content.mode` | Set to `static`. | | `content.phrases` | The filler phrases, 1 to 100 non-empty strings. | | `content.selection_rule` | How the agent picks the next phrase: `shuffle` (random order, the default) or `round_robin` (list order, starting over after the last phrase). | ## Configure generated filler words To have Agora generate a phrase that fits the conversation, use the same settings with the content mode set to `generated`. Generated mode requires the agent's LLM to use your own key with OpenAI, Groq, or xAI. With a managed LLM, the request is rejected. For details, see [Use your own provider keys](/en/ai/platform/build/use-your-own-keys). In the instructions, describe the kind of phrase to generate. Set the fallback strategy to `static` to use a static phrase when a generated one isn't ready in time. **Python SDK** Put the instructions in `generated_config.prompt`. This example assumes that `agent` uses your own OpenAI key, as in [Use the key in an agent](/en/ai/platform/build/use-your-own-keys#use-the-key-in-an-agent). ```python generated_filler_agent = agent.with_filler_words( { "enable": True, "trigger": { "mode": "fixed_time", "fixed_time_config": {"response_wait_ms": 1500}, }, "content": { "mode": "generated", "generated_config": { "prompt": "Generate a short, natural filler phrase that shows you're working on the request. Don't answer the question.", "fallback_strategy": "static", }, }, } ) ``` **TypeScript SDK** Put the instructions in `generated_config.prompt`. This example assumes that `agent` uses your own OpenAI key, as in [Use the key in an agent](/en/ai/platform/build/use-your-own-keys#use-the-key-in-an-agent). ```ts const generatedFillerAgent = agent.withFillerWords({ enable: true, trigger: { mode: 'fixed_time', fixed_time_config: { response_wait_ms: 1500 }, }, content: { mode: 'generated', generated_config: { prompt: "Generate a short, natural filler phrase that shows you're working on the request. Don't answer the question.", fallback_strategy: 'static', }, }, }); ``` **Go SDK** Put the instructions in `GeneratedConfig.Prompt`. This example assumes that `agent` uses your own OpenAI key, as in [Use the key in an agent](/en/ai/platform/build/use-your-own-keys#use-the-key-in-an-agent). ```go generatedFillerAgent := agent.WithFillerWords(&agentkit.FillerWordsConfig{ Enable: Agora.Bool(true), Trigger: &agentkit.FillerWordsTrigger{ Mode: Agora.String("fixed_time"), FixedTimeConfig: &agentkit.FillerWordsTriggerFixedTimeConfig{ ResponseWaitMs: Agora.Int(1500), }, }, Content: &agentkit.FillerWordsContent{ Mode: agentkit.FillerWordsContentModeGenerated.Ptr(), GeneratedConfig: &agentkit.FillerWordsContentGeneratedConfig{ Prompt: Agora.String("Generate a short, natural filler phrase that shows you're working on the request. Don't answer the question."), FallbackStrategy: agentkit.FillerWordsFallbackStrategyStatic.Ptr(), }, }, }) ``` **REST API** ```json "filler_words": { "enable": true, "trigger": { "mode": "fixed_time", "response_wait_ms": 1500 }, "content": { "mode": "generated", "instructions": "Generate a short, natural filler phrase that shows you're working on the request. Don't answer the question.", "fallback_strategy": "static" } } ``` | Field | Description | | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `content.mode` | Set to `generated`. | | `content.instructions` | Required. The instructions used to generate filler phrases. You can use the agent's variables in them, for example `{{customer_name}}`. For details, see [Personalize conversations](/en/ai/platform/build/shape-the-conversation/personalize-conversations). | | `content.fallback_strategy` | What to use when a generated phrase isn't available. Set to `static`. | The `enable` and `trigger` fields work the same way as for static filler words. ## Best practices Keep the following tips in mind when configuring filler words: - **Keep phrases short and natural**: Use brief, conversational phrases that sound like something a person would say. - **Match phrasing to your use case**: For customer support agents, use reassuring phrases like "Let me look into that for you." For casual assistants, use informal phrases like "Hmm, one sec." - **Tune the trigger threshold**: Start with a `response_wait_ms` of 1500 ms, and adjust it based on your LLM's typical response time. If your agent often calls tools, consider a lower threshold to cover the longer waits. - **Provide enough variety**: Include at least 4 to 6 phrases to avoid sounding repetitive. Use `shuffle` to vary the phrases across turns. ## Reference For more information, see the following pages: - [Personalize conversations](/en/ai/platform/build/shape-the-conversation/personalize-conversations) ### API reference - [Create an agent](/en/api-reference/api-ref/conversational-ai/platform/create-agent) - [Update an agent](/en/api-reference/api-ref/conversational-ai/platform/update-agent)