;
};
**Level 2 – Lesson 4 of 8** – Master response controls to regulate agent output and enforce tone.
[Response Controls](/voice-channel/advanced/response-control) regulate the agent's *own output*. They run **after** the model generates text and **before** anything is spoken or sent. Useful for tone, safety, and flow – easy to misuse if patterns are too broad.
## What response controls are
Response Controls are **string- or regex-based rules** that inspect the agent's generated response.
Prevent specific phrases from being spoken
Activate corrective or fallback behavior
Track unwanted patterns for analysis
Maintain brand voice consistency
Response controls are not about what the *user* says – they are about what the *agent* says.
## Which tool to use for which problem
```mermaid theme={"theme":{"light":"github-light","dark":"github-dark"}}
flowchart TD
A[Unwanted agent behavior] --> B{What type of problem?}
B -->|ASR mishears user| C[Use ASR tools / Keyphrase Boosting]
B -->|Wrong topic retrieved| D[Fix Managed Topic name or sample questions]
B -->|Agent says something it shouldn't| E[Use Response Controls]
E --> F{Should phrase NEVER appear?}
F -->|Yes| G[Halt – set Say phrases: TRUE]
F -->|No, just monitor it| H[Log – set Say phrases: FALSE]
G --> I{Needs a fallback action?}
I -->|Yes| J[Attach a function]
I -->|No| K[Done]
```
## When to use response controls
Use response controls when you want to fix or prevent:
**Examples:**
* "Let me check that for you…"
* "Please hold while I look into this…"
**Examples:**
* Repeating the greeting mid-call
* Restarting the conversation after silence
**Examples:**
* Overly apologetic language
* Internal system explanations
**Examples:**
* Speculation
* Policy invention
* Meta commentary about limitations
* If the issue is about *recognition*, use ASR tools
* If the issue is about *retrieval*, fix the FAQs
* If the issue is about *how the agent speaks*, use Response Controls
## How response controls work
The model creates text based on context and prompts
Regex patterns are evaluated against the generated text
* The response may be halted
* A function may be triggered
* The event may be logged for analytics
Controls are evaluated in real time and apply consistently across Chat and Call.
## Check your understanding
## Core fields
Each Response Control includes:
A short, descriptive identifier used for tracking and debugging.
Optional, but strongly recommended. Explains *why* the rule exists.
The exact pattern that will be matched against agent output.
Despite the name, this field controls **halting**, not allowing:
* **ON (Halt)**: matching output is **blocked** before it reaches the user
* **OFF (Log)**: matching output is **allowed through** but recorded for analytics
A fallback action to run when the phrase is detected.
## Best practices
Broad patterns are hard to debug and can suppress valid responses.
`.*sorry.*`
`\b(sorry for the inconvenience|apologies for the delay)\b`
Encode *specific phrases* you have observed, not abstract concepts.
"Prevent the agent from being verbose"
`\b(let me explain how|to give you some background)\b`
If a phrase should *never* appear, halt it rather than replacing it.
Verify in both Chat and Call to catch unnatural truncation.
## Common use cases
LLMs often add filler before answering or executing actions.
**Example unwanted output:**
"Let me check that for you. Please hold…"
**Suggested control:**
* **ID:** `flow_redundancy_cutoff`
* **Regex:** `\b(let me check|please hold|one moment while I)\b`
* **Say phrases:** TRUE
**Result:** The agent proceeds directly to the answer or action.
Sometimes the agent restarts the conversation mid-call.
**Example unwanted output:**
"Thank you for calling Hopper…"
**Suggested control:**
* **ID:** `greet_loop`
* **Regex:** `(thank you for calling|you have reached|hi thanks for calling)`
* **Say phrases:** TRUE
You can optionally attach a function that routes to a recovery flow instead of restarting.
Agents sometimes respond with unhelpful refusals instead of routing.
**Example unwanted output:**
"I don't have information about that."
**Suggested control:**
* **ID:** `default_no_info`
* **Regex:** `I don't have (any|specific)? information`
* **Say phrases:** TRUE
* **Function:** `prompt_OOS_Check`
**Result:** Instead of dead-ending, the agent routes to out-of-scope handling.
Prevent phrasing that violates brand voice.
**Example unwanted output:**
"Unfortunately, I'm unable to…"
**Suggested control:**
* **ID:** `tone_softener`
* **Regex:** `\b(unfortunately|sadly|regret to inform)\b`
* **Say phrases:** TRUE
**Result:** Forces the agent to rephrase without negative framing.
## Logging-only controls
Not all controls need to halt output. You can use Response Controls purely for **monitoring**.
* **ID:** `hedge_language_monitor`
* **Regex:** `\b(might|maybe|possibly)\b`
* **Say phrases:** FALSE
Tracks hedging frequency without disrupting users.
## Testing and verification
After adding or updating a Response Control:
* Confirm the phrase no longer appears
* Ensure the response still completes cleanly
* Listen for unnatural truncation
* Ensure turn-taking still feels natural
* Check whether the rule is triggering too often
* Look for false positives
## Common mistakes
**Avoid these pitfalls:**
* Using overly broad regex patterns
* Blocking phrases that appear in legitimate answers
* Using Response Controls to fix retrieval problems
* Forgetting to test in voice after chat validation
## Check your understanding
## Pronunciations (separate feature)
Affect *what* is said
Affect *how* it is spoken
Use **Pronunciations** when:
* Names are mispronounced
* Numbers need pacing
* Domain terms require IPA or SSML guidance
Do not use Response Controls to solve pronunciation issues.
Response Controls are a surgical tool – the final layer of polish, not the first fix.
## Try it yourself
You notice the agent frequently says "Let me look into that for you" before answering – which creates an awkward pause in voice calls.
Write the full Response Control configuration:
1. ID
2. Description
3. Regex
4. Say phrases setting
Write the regex to match the specific phrase you observed, not a broad pattern. Start as narrow as possible – you can always widen it if needed.
* **ID:** `filler_preamble_cutoff`
* **Description:** Prevents the agent from saying "Let me look into that for you" before responding – this creates latency and sounds unnatural in voice.
* **Regex:** `\blet me (look into|check) that for you\b`
* **Say phrases:** TRUE
## Check your understanding
Lesson 3 of 8
Lesson 5 of 8