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Syllable

Syllable is a Mountain View, California company (founded 2017) that operates an agentic platform for building, deploying and optimizing AI voice, SMS, email, web-chat and WhatsApp agents, with a strong focus on healthcare patient experience and contact-center automation. The Syllable Platform SDK exposes a REST API at api.syllable.cloud covering agents, prompts, tools, services, data sources, channels and channel targets, sessions and transcripts, outbound campaigns and batches, insights workflows, directory, dashboards, incidents, organizations, roles, permissions and users. First-party TypeScript and Python SDKs, a Go CLI, a documentation MCP server and a published A2A agent card make it an unusually agent-forward developer surface.

agent ready

Solid contracts, transparent operations, and an easy start — typically complete on four or five facets with one clear soft spot.

Kin Score
travel_explore apis.io index code GitHub sourcepublic Website

API Evangelist profiles Syllable the way a machine reads it — 89 machine-readable artifacts across 41 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.

Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Syllable scores 59.5/100 (strong), with a separate agent-readiness read of 53/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.

Kin Score

This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.

Kin Score Kin Score How this is scored →
scored 2026-08-17 · rubric v0.11.0
Composite quality — 59.5/100 · strong
Contract Quality 16.7 / 25
Developer Ergonomics 17.4 / 20
Commercial Clarity 12.1 / 20
Operational Transparency 5.8 / 13
Governance 2.5 / 12
Discoverability 8.2 / 10
Regulatory · Telecommunications 6.3 / 15
Agent readiness — 53/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract derived 2.5 / 10
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8.0 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface derived 1.5 / 6
Agent Skills 5 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card flavored 2.0 / 8
Dry-Run / Simulate Mode 0 / 4
Syllable Kin Score — API readiness rating by API Evangelist

Put this on your own site. The badge is drawn live from Syllable's current Kin Score — paste it once and it updates itself every time the score is recomputed. It follows your visitor's light or dark setting, and it links back here so anyone who sees it can read the full breakdown.

<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/syllable/"
   title="Syllable on API Evangelist — API profile and Kin Score">
  <img src="https://apis.io/badge/syllable.svg"
       alt="Syllable Kin Score — API readiness rating by API Evangelist" width="150" height="150" loading="lazy">
</a>

More shapes, themes and sizes → · Score as JSON · How badges work

How we profile Syllable

Each block below is one kind of artifact we hold for Syllable. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.

APIs 41

Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.

Individual APIs this provider publishes, each with its own machine-readable definition.

Syllable Agents API

Operations related to agent configuration. When a user interacts with the Syllable system, they do so by communicating with an agent. An agent is linked to a prompt, a custom me...

Syllable Agents.test API

Operations for testing agents with live text. These endpoints allow sending messages to an agent and receiving its responses.

Syllable Bridge Phrases API

The bridge_phrases API from Syllable — 2 operation(s) for bridge_phrases.

Syllable Channels API

Operations related to channel configuration. A channel is an organization-level point of communication, like a phone number or a web chat. A channel can be associated with an ag...

Syllable Channels.targets API

Operations related to channel target configuration. A channel target links a channel to an agent, allowing users to communicate with the agent through that channel. For more inf...

Syllable Channels.twilio API

Operations related to Twilio channel configuration.

Syllable Channels.twilio.numbers API

Operations related to setting up phone numbers in Twilio for use in channels.

Syllable Conversation Config API

The conversation-config API from Syllable — 1 operation(s) for conversation-config.

Syllable Conversations API

Operations related to conversations. A conversation is a record of messages between a user and an agent, and is composed of one or more sessions.

Syllable Custom Messages API

Operations related to custom message configuration. A custom message is a pre-configured message delivered by an agent as a greeting at the beginning of a conversation. Multiple...

Syllable Dashboards API

Operations related to dashboards. Currently the API/SDK only supports fetching basic information about dashboards.

Syllable Data Sources API

Operations related to data sources. A data source is a blob of text that can be made available to an agent's general info tools to provide more context to the agent when generat...

Syllable Directory API

Operations related to directory

Syllable Events API

Operations related to events. An event represents a specific occurrence during a session. Currently the API/SDK only supports fetching logged events.

Syllable Incidents API

Operations related to incidents.

Syllable Insights API

Operations related to insights results. An insight is a tool that processes conversation data to extract information and generate reports.

Syllable Insights.folders API

Operations related to insights upload folders. An insight folder is used to upload call recordings for insight workflow analysis.

Syllable Insights.tools API

Operations related to insights tool configurationss. An insight is a tool that processes conversation data to extract information and generate reports.

Syllable Insights.workflows API

Operations related to insights workflows. An workflow is series of tool invocations that processes conversation data to extract information and generate reports.

Syllable Language Groups API

Operations related to language groups. A language group is a collection of language, voice, and DTMF configuration that can be linked to an agent to define the languages and voi...

Syllable Organizations API

Operations related to organizations.

Syllable Organizations.sip Ip Ranges API

The organizations.sip_ip_ranges API from Syllable — 2 operation(s) for organizations.sip_ip_ranges.

Syllable Outbound.batches API

Operations related to outbound campaign batches

Syllable Outbound.campaigns API

Operations related to outbound message campaigns

Syllable Permissions API

Operations related to permissions. A permission is a specific capability or access level granted to a user within the Syllable system. Permissions are used to control access to ...

Syllable Prompts API

Operations related to prompts. A prompt defines the behavior of an agent by delivering instructions to the LLM about how the agent should behave. A prompt can be linked to one o...

Syllable Pronunciations API

The pronunciations API from Syllable — 3 operation(s) for pronunciations.

Syllable Roles API

Operations related to roles. A role is a collection of permissions that can be assigned to users to control their access to various features within the Syllable system.

Syllable Services API

Operations related to service configuration. A service is a collection of tools. You can specify an authentication method and values on a service, and any linked tools will use ...

Syllable Session Debug API

The session_debug API from Syllable — 3 operation(s) for session_debug.

Syllable Session Labels API

Operations related to labeling sessions with evaluations of quality and descriptions of issues the user encountered or other details. For more information, see [Console docs](ht...

Syllable Sessions API

Operations related to sessions. A session is a building block of a conversation. For more information, see [Console docs](https://docs.syllable.ai/workspaces/Sessions).

Syllable Sessions.full Summary API

The sessions.full-summary API from Syllable — 1 operation(s) for sessions.full-summary.

Syllable Sessions.latency API

The sessions.latency API from Syllable — 1 operation(s) for sessions.latency.

Syllable Sessions.timeline API

The sessions.timeline API from Syllable — 1 operation(s) for sessions.timeline.

Syllable Sessions.transcript API

The sessions.transcript API from Syllable — 1 operation(s) for sessions.transcript.

Syllable Takeouts API

The takeouts API from Syllable — 3 operation(s) for takeouts.

Syllable Tools API

Operations related to tool configuration. A tool is a function that an agent can call to perform actions like accessing databases, making API calls, or processing data. For an a...

Syllable Users API

The users API from Syllable — 4 operation(s) for users.

Syllable V1 API

The V1 API from Syllable — 4 operation(s) for v1.

Syllable Voice Groups API

The voice_groups API from Syllable — 3 operation(s) for voice_groups.

Scroll within the panel for all 41 ·

Open Collections 42

Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

SyllableSDK Agents API

OPEN COLLECTION

SyllableSDK Agents.test API

OPEN COLLECTION

SyllableSDK Bridge Phrases API

OPEN COLLECTION

SyllableSDK Channels API

OPEN COLLECTION

SyllableSDK Channels.targets API

OPEN COLLECTION

SyllableSDK Channels.twilio API

OPEN COLLECTION

SyllableSDK Channels.twilio.numbers API

OPEN COLLECTION

SyllableSDK Conversation Config API

OPEN COLLECTION

SyllableSDK Conversations API

OPEN COLLECTION

SyllableSDK Custom Messages API

OPEN COLLECTION

SyllableSDK Dashboards API

OPEN COLLECTION

SyllableSDK Data Sources API

OPEN COLLECTION

SyllableSDK Directory API

OPEN COLLECTION

SyllableSDK Events API

OPEN COLLECTION

SyllableSDK Incidents API

OPEN COLLECTION

SyllableSDK Insights API

OPEN COLLECTION

SyllableSDK Insights.folders API

OPEN COLLECTION

SyllableSDK Insights.tools API

OPEN COLLECTION

SyllableSDK Insights.workflows API

OPEN COLLECTION

SyllableSDK Language Groups API

OPEN COLLECTION

SyllableSDK Organizations API

OPEN COLLECTION

SyllableSDK Organizations.sip Ip Ranges API

OPEN COLLECTION

SyllableSDK Outbound.batches API

OPEN COLLECTION

SyllableSDK Outbound.campaigns API

OPEN COLLECTION

SyllableSDK Permissions API

OPEN COLLECTION

SyllableSDK Prompts API

OPEN COLLECTION

SyllableSDK Pronunciations API

OPEN COLLECTION

SyllableSDK Roles API

OPEN COLLECTION

SyllableSDK Services API

OPEN COLLECTION

SyllableSDK Session Debug API

OPEN COLLECTION

SyllableSDK Session Labels API

OPEN COLLECTION

SyllableSDK Sessions API

OPEN COLLECTION

SyllableSDK Sessions.full Summary API

OPEN COLLECTION

SyllableSDK Sessions.latency API

OPEN COLLECTION

SyllableSDK Sessions.timeline API

OPEN COLLECTION

SyllableSDK Sessions.transcript API

OPEN COLLECTION

SyllableSDK Takeouts API

OPEN COLLECTION

SyllableSDK Tools API

OPEN COLLECTION

SyllableSDK Users API

OPEN COLLECTION

SyllableSDK V1 API

OPEN COLLECTION

SyllableSDK Voice Groups API

OPEN COLLECTION

Scroll within the panel for all 42 ·

MCP Servers 1

Model Context Protocol servers expose these APIs directly to AI agents. We profile them because agent-native access is the fastest-growing way this provider's capabilities actually get used.

Model Context Protocol servers that expose these APIs to AI agents.

syllable-mcp.yml

MCP SERVER

Event Specifications 1

Not every API is request/response. AsyncAPI describes the event-driven and streaming side — the webhooks and channels — so the asynchronous half of the interface is documented the same way the synchronous half is.

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Syllable Outbound Webhooks

ASYNCAPI

Security Posture 3

Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Syllable Authentication

apiKey · 1 scheme

SECURITY

Syllable Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Syllable Trust Center

SOC 2 Type 2, HIPAA, HITRUST, GDPR

SECURITY

Agentic Access 1

An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.

Recommended x-agentic-access execution contracts for AI agents.

Syllable Agentic Access

176 operations · 98 acting

176 operations · 98 acting

AGENTIC

Resources

Every other property we hold for Syllable — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.

Get Started 5

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 SignUp
SignUp
 Login
Login
 Sandbox
Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess
AgenticAccess
 MCPServer
MCPServer
 AgentSkill
AgentSkill
 LLMsTxt
LLMsTxt
 WellKnown
WellKnown

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 Conformance
Conformance
 DataModel
DataModel
 Components
Components
 Webhooks
Webhooks

Scroll within the panel for all 7 ·

Build 5

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 Packages
Packages
 SDKs
SDKs
 CLI
CLI
 ToolCrosswalk
ToolCrosswalk

Access & Security 4

Authentication, authorization, and security posture

TrustCenter
TrustCenter
 DomainSecurity
DomainSecurity
 Compliance
Compliance
 Authentication
Authentication

Operate 4

Status, limits, changes, and where to get help

Support
Support
 StatusPage
StatusPage
 ChangeLog
ChangeLog
 ChangeLog
ChangeLog

Commercial 3

Pricing, plans, and the legal terms of use

Pricing
Pricing
 TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy

Company 2

The organization behind the API

Website
Website
 Blog
Blog

Other 2

Properties that don't map to a standard resource type

Overlay
Overlay
 AgentCard
AgentCard

← All providers · Data indexed from github.com/api-evangelist/syllable · machine-readable index on apis.io

Where this information came from

This is an independent, third-party profile of Syllable, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.

The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.

Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.

info@apievangelist.com · Read the full data-sourcing policy →
On a security or compliance team? Put security in the subject line and you will get a person, not a form — we will tell you exactly which public URLs this profile was built from.