Amazon Lex Runtime V2

Name: Amazon Lex Runtime V2 API
Brand: Amazon Lex Runtime V2
Availability: InStock

★ Only Publicly Available SpecAI/MLLanguage Modelshmac5 EndpointsREST

For Agents

Send user text or audio to a deployed Lex V2 bot and receive recognised intents, slot values, and the bot's next conversational response.

Quickstart

Get started with Amazon Lex Runtime V2 in minutes using your preferred integration method.

# Add to your MCP client config (Claude Desktop, Cursor, Windsurf)
{
  "jentic": {
    "url": "https://api.jentic.com/mcp",
    "auth": "oauth"
  }
}

# Then ask your agent:
"send text to a Lex V2 bot"

# → Jentic returns the GET /events tool with parameter schema, agent executes.

Capabilities

What an agent can do with Amazon Lex Runtime V2 API.

Send a text utterance to a Lex V2 bot and receive intent, slot values, and response messages with RecognizeText

Stream an audio utterance to a Lex V2 bot for speech-to-intent recognition with RecognizeUtterance

Read the current state of a conversational session including recognised intents and active context with GetSession

Set or override session state including slots, context, and session attributes with PutSession

GET STARTED

Start building with Amazon Lex Runtime V2 API

Explore with Jentic

View OpenAPI Spec

Use for: Send a user message to a Lex V2 bot and get the recognised intent, Stream audio to a Lex V2 bot for voice-driven intent recognition, Get the current dialog state for an in-progress Lex conversation, Reset a user's Lex session so the next turn starts fresh

Not supported: Does not build or train bots, manage intents and slots at design time, or synthesise standalone speech — use for sending user utterances to a deployed Lex V2 bot and reading or overriding session state only.

Jentic publishes the only available OpenAPI specification for Amazon Lex Runtime V2, keeping it validated and agent-ready.

Jentic publishes the only available OpenAPI specification for Amazon Lex Runtime V2, keeping it validated and agent-ready. Lex Runtime V2 is the conversational dataplane for Amazon Lex V2 bots — it exchanges user text or audio with a deployed bot alias and returns recognised intents, slot values, and the bot's next response. The runtime carries session state across turns, supports both text and streaming utterance recognition, and is the integration point for chat widgets, IVR systems, and voice assistants built on Lex V2.

Use Cases

Patterns agents use Amazon Lex Runtime V2 API for, with concrete tasks.

★ Text chatbot integration

Product teams use RecognizeText to wire a Lex V2 bot into a web chat widget or messaging integration. Each user message becomes a POST to /text with botId, botAliasId, localeId, and sessionId; the response includes the recognised intent, slot values, and the bot's outbound message — enough to render the next turn of conversation without managing dialogue state in the application.

Call RecognizeText with botId='ABC123', botAliasId='TSTALIASID', localeId='en_US', sessionId='user-42', and text='I want to book a flight to Paris', then return the recognised intent and slot values.

Voice IVR and contact-centre integration

Contact-centre teams use RecognizeUtterance to stream caller audio to a Lex V2 bot and get back both the recognised intent and a synthesised audio response, all in one call. The runtime accepts standard PCM and Opus audio formats and returns the bot's reply as audio bytes plus structured intent data, which makes it the integration point for Amazon Connect IVR flows and other voice channels.

Stream an Opus-encoded user utterance to RecognizeUtterance for the customer-service bot alias and play the returned audio response back to the caller.

Session state management for multi-turn flows

Application teams use GetSession and PutSession to inspect and override the dialog state mid-conversation — useful for hand-offs to human agents, prefilling slots from a CRM lookup, or steering the bot toward a specific intent based on user context. DeleteSession clears state at logout or session timeout. This makes Lex V2 sessions deterministic and inspectable rather than a black box.

Call PutSession to seed slot values customerName='Jane Doe' and accountId='987654' before the next user turn, then RecognizeText with the user's actual message.

Agent-driven conversational flows through Jentic

AI agents that orchestrate hybrid LLM + Lex V2 flows use Jentic to call RecognizeText and PutSession without holding raw AWS credentials. Jentic stores keys in the MAXsystem vault, signs each request with SigV4, and returns the structured intent and slot data — letting the agent decide whether to defer to Lex's deterministic intent matching or fall back to its own reasoning.

Search Jentic for 'send text to a Lex V2 bot', load RecognizeText, and execute against the support-bot alias with the user's last message, returning the recognised intent for downstream routing.

Key Endpoints

5 endpoints — jentic publishes the only available openapi specification for amazon lex runtime v2, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}/text

Send a text utterance and receive intent and response

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}/utterance

Send an audio utterance and receive intent plus audio response

GET

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Read current session state

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Set or override session state

DELETE

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Delete a session and reset state

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}/text

Send a text utterance and receive intent and response

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}/utterance

Send an audio utterance and receive intent plus audio response

GET

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Read current session state

POST

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Set or override session state

DELETE

/bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}

Delete a session and reset state

Why though Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

AWS credentials are stored encrypted in the Jentic vault (MAXsystem). Each Lex Runtime V2 call is signed with SigV4 server-side and the agent only receives scoped, short-lived authorisation — raw access keys never enter the agent's context.

Intent-based discovery

Agents search by intent (e.g., 'send text to a Lex V2 bot') and Jentic returns matching runtime operations with their input schemas, so the agent calls RecognizeText or PutSession without browsing AWS docs.

Time to first call

Direct Lex Runtime V2 integration: 1-2 days for SigV4 signing, audio streaming, and session-state plumbing. Through Jentic: under 30 minutes for the API surface — search, load schema, execute.

Related APIs

Alternatives and complements available in the Jentic catalogue.

Complementary

Amazon Lex Models V2

The build-time API for defining intents, slots, and bot versions that the runtime then serves

Use Models V2 to author and version a bot; use Runtime V2 to send actual user utterances to a deployed alias.

Complementary

Amazon Polly

Polly synthesises text-to-speech for bot responses when not using RecognizeUtterance's audio output

Use Polly when you want to synthesise the bot's text response into custom-voiced audio outside the Lex audio pipeline.

Alternative

Amazon Lex Models V1

The earlier Lex V1 modelling API — V2 is the current recommended platform

Choose Lex V1 only for legacy bots already built on V1; new development should use Lex V2 (modelslexv2 + runtimelexv2).

FAQs

Specific to using Amazon Lex Runtime V2 API through Jentic.

Why is there no official OpenAPI spec for Amazon Lex Runtime V2?

AWS does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Amazon Lex Runtime V2 via structured tooling. It is validated against the live API and kept up to date. Get started at https://app.jentic.com/sign-up.

What authentication does the Amazon Lex Runtime V2 API use?

Lex Runtime V2 uses AWS Signature Version 4 HMAC signing with an access key ID and secret access key, optionally with a session token. Through Jentic, those credentials live in the MAXsystem vault and the agent never handles raw secrets — Jentic signs each request server-side.

Can I build or train a Lex V2 bot with the Amazon Lex Runtime V2 API?

No. The runtime is for sending utterances to an already-deployed bot alias and reading dialog state. Building intents, slots, and bot versions is done through the separate Lex Models V2 API (modelslexv2 in this catalogue) — runtime and modelling are split into two services.

What are the rate limits for the Amazon Lex Runtime V2 API?

AWS publishes default soft limits per bot alias for RecognizeText and RecognizeUtterance, typically in the tens of TPS, with higher limits available on request. The exact numbers are not in the spec — check the AWS service quotas console for your account, and back off on ThrottlingException.

How do I send a user message to a Lex bot through Jentic?

Search Jentic for 'send text to a Lex V2 bot', load RecognizeText, and call POST /bots/{botId}/botAliases/{botAliasId}/botLocales/{localeId}/sessions/{sessionId}/text with a JSON body containing the user's text. The response returns the recognised intent, slot values, and bot messages. Install with pip install jentic.

How does Lex V2 maintain conversation context across turns?

Lex V2 keys conversation state on sessionId, scoped by botId, botAliasId, and localeId. As long as the client sends the same sessionId on each call, the runtime carries slots, dialog state, and session attributes across turns. Use GetSession to inspect the state and DeleteSession to reset it.