Hail

Hail provides a unified API that gives AI agents a phone number and email inbox, enabling them to make and receive calls, send and receive SMS, and manage email. The platform offers easy integration for developers building AI assistants, with features like call routing, message handling, and customizable agent behavior. It targets developers seeking to add communication capabilities to AI applications, offering a simple RESTful interface and comprehensive documentation.

Hail publishes 17 API contracts indexed on the APIs.io network, including Agents API, Calls API, Contacts API, and 14 more. Tagged areas include Artificial Intelligence, Communications, Phone, SMS, and Email.

The Hail catalog on APIs.io includes 1 event-driven AsyncAPI specification, 1 JSON-LD context, and 1 Spectral governance ruleset.

Hail’s developer surface includes CLI, pricing, documentation, engineering blog, getting-started guide, API reference, and 22 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

43.7/100 developing Agent 52/100 agent native Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

1 published contract 2 Agent Skills

Artificial Intelligence Communications Phone SMS Email

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 43.7/100 · developing

Contract Quality 14.1 / 21

Developer Ergonomics 6.8 / 17

Access Clarity 6.2 / 17

Operational Transparency 1.6 / 11

Contract Governance 3.6 / 10

Discoverability 5.6 / 9

Regulatory Posture 2.2 / 15

Agent readiness — 52/100 · agent native

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Telecommunications regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Show this score on your site.

It updates itself when the score changes. Paste this where you link to your API docs:

<a href="https://apis.io/providers/hail-so/"><img src="https://apis.io/badge/hail-so/card.svg" alt="Hail on APIs.io — Kin Score by API Evangelist"></a>

Other styles, a README pill and a shields.io endpoint are on the badge page.

Raise your score.

Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →
Documented Reversibility +6 pts — a reversal operation in the contract, graded up when a window is documented too Ask about this →
Protected Resource Metadata +5 pts — a served /.well-known/oauth-protected-resource carrying `resource` (documented), and naming its authorization_servers (verified) Ask about this →
Agentic Commerce Well-Known Document +5 pts — a parsing /.well-known/ucp.json or acp.json declaring a version and at least one service, OR (0.27) a live x402 payment challenge from _data/x402-adoption.json — `self` when its endpoints are on the provider's own domain, `platform` when they are on a vendor's Ask about this →

3 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 36.2 — up to +12.8 composite points Ask about this →
Developer Ergonomics scores 39.9 — up to +12.0 composite points Ask about this →
Operational Transparency scores 14.3 — up to +11.1 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/hail-so/apis.yml: open an issue on github.com/api-evangelist/hail-so to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Dynamic Client Registration

measured — observed by APIs.io (published)

OpenAPI

measured — observed by APIs.io (published)

APIs 17

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

Hail Agents API

The agents API from Hail — 2 operation(s) for agents.

Hail Calls API

The calls API from Hail — 3 operation(s) for calls.

Hail Contacts API

The contacts API from Hail — 3 operation(s) for contacts.

Hail Email Attachments API

The email-attachments API from Hail — 1 operation(s) for email-attachments.

Hail Email Domains API

The email-domains API from Hail — 5 operation(s) for email-domains.

Hail Emails API

The emails API from Hail — 8 operation(s) for emails.

Hail Events API

The events API from Hail — 1 operation(s) for events.

Hail Forward Targets API

The forward-targets API from Hail — 2 operation(s) for forward-targets.

Hail Healthz API

The Healthz API from Hail — 1 operation(s) for healthz.

Hail Numbers API

The numbers API from Hail — 6 operation(s) for numbers.

Hail Providers API

The providers API from Hail — 5 operation(s) for providers.

Hail Sms API

The sms API from Hail — 5 operation(s) for sms.

Hail Unsubscribe API

The unsubscribe API from Hail — 1 operation(s) for unsubscribe.

Hail Uploads API

The uploads API from Hail — 2 operation(s) for uploads.

Hail Verifications API

The verifications API from Hail — 9 operation(s) for verifications.

Hail Webhooks API

The webhooks API from Hail — 6 operation(s) for webhooks.

Hail Whoami API

The whoami API from Hail — 1 operation(s) for whoami.

Scroll for all 17

Agent Skills 2

Packaged agent skills for driving this provider's APIs from an AI assistant.

hail-so-acquire-and-enable-sms

AGENT SKILL

hail-so-manage-webhook-subscription

AGENT SKILL

Event Specifications 1

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

Hail So Webhooks

ASYNCAPI

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Hail So Context

100 classes · 278 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

Hail API Rules

50 rules · 36 error-severity 13 warn-severity 1 info-severity

SPECTRAL

JSON Schema 6

Standalone JSON Schema definitions for this provider's data models.

CallCreate

15 properties

JSON SCHEMA

CallResponse

20 properties

JSON SCHEMA

EmailCreate

15 properties

JSON SCHEMA

EmailDomainResponse

18 properties

JSON SCHEMA

EmailResponse

32 properties

JSON SCHEMA

VerificationResponse

20 properties

JSON SCHEMA

Security Posture 1

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

Hail Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

Hail Agentic Access

85 operations · 43 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

Login

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgentSkill

LLMsTxt

WellKnown

Design & Contract 10

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

Webhooks

DataModel

Idempotency

Conventions

Lifecycle

ErrorCatalog

Conformance

Scroll for all 10

Build 1

SDKs, sample code, and the tooling you integrate with

CLI

CLI

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Deprecation

Deprecation

Commercial 3

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Pricing

Pricing

Company 2

The organization behind the API

Blog

Blog

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: hail-so
name: Hail
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - security
  generated: '2026-11-13'
  method: derived
image: https://hail.so/opengraph-image
description: Hail provides a unified API that gives AI agents a phone number and email inbox, enabling them to make and receive
  calls, send and receive SMS, and manage email. The platform offers easy integration for developers building AI assistants,
  with features like call routing, message handling, and customizable agent behavior. It targets developers seeking to add
  communication capabilities to AI applications, offering a simple RESTful interface and comprehensive documentation.
url: https://artifacts.apis.io/hail-so/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-11 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-11-10'
modified: '2026-11-10'
tags:
- Artificial Intelligence
- Communications
- Phone
- SMS
- Email
tags_raw:
- AI
- Communications
- Phone
- SMS
- Email
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/hail-so-agentic-access.yml
- type: Spectral
  url: rules/hail-so-rules.yml
- type: JSONLD
  url: json-ld/hail-so-context.jsonld
- type: Vocabulary
  url: vocabulary/hail-so-vocabulary.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Webhooks
  url: asyncapi/hail-so-webhooks.yml
- type: DataModel
  url: data-model/hail-so-data-model.yml
- type: CLI
  url: cli/hail-so-cli.yml
- type: Idempotency
  url: conventions/hail-so-conventions.yml
- type: Conventions
  url: conventions/hail-so-conventions.yml
- type: Deprecation
  url: lifecycle/hail-so-lifecycle.yml
- type: Lifecycle
  url: lifecycle/hail-so-lifecycle.yml
- type: ErrorCatalog
  url: errors/hail-so-problem-types.yml
- type: Conformance
  url: conformance/hail-so-conformance.yml
- type: LLMsTxt
  url: llms/hail-so-llms.txt
- type: WellKnown
  url: well-known/hail-so-well-known.yml
- type: Hosts
  url: hosts/hail-so-hosts.yml
- type: Vendors
  url: vendors/hail-so-vendors.yml
- type: TermsOfService
  url: https://hail.so/legal/terms
- type: PrivacyPolicy
  url: https://hail.so/legal/privacy
- type: Pricing
  url: https://hail.so/pricing
- type: Login
  url: https://hail.so/signin
- type: Documentation
  url: https://hail.so/docs
- type: Blog
  url: https://hail.so/blog
- type: GettingStarted
  url: https://hail.so/create-ai-agent#ai-agent-setup-faq
- type: APIReference
  url: https://hail.so/docs/api
- type: DomainSecurity
  url: security/hail-so-domain-security.yml
- type: Website
  url: https://hail.so/
apis:
- aid: hail-so:hail-so-agents-api
  name: Hail Agents API
  description: The agents API from Hail — 2 operation(s) for agents.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Agents
  tags_raw:
  - agents
  properties:
  - type: OpenAPI
    url: openapi/hail-so-agents-api-openapi.yml
- aid: hail-so:hail-so-calls-api
  name: Hail Calls API
  description: The calls API from Hail — 3 operation(s) for calls.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Calls
  tags_raw:
  - calls
  properties:
  - type: OpenAPI
    url: openapi/hail-so-calls-api-openapi.yml
  - type: JSONSchema
    url: json-schema/hail-so-call-create-schema.json
  - type: JSONSchema
    url: json-schema/hail-so-call-response-schema.json
- aid: hail-so:hail-so-contacts-api
  name: Hail Contacts API
  description: The contacts API from Hail — 3 operation(s) for contacts.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Contacts
  tags_raw:
  - contacts
  properties:
  - type: OpenAPI
    url: openapi/hail-so-contacts-api-openapi.yml
- aid: hail-so:hail-so-email-attachments-api
  name: Hail Email Attachments API
  description: The email-attachments API from Hail — 1 operation(s) for email-attachments.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - EmailAttachments
  tags_raw:
  - email-attachments
  properties:
  - type: OpenAPI
    url: openapi/hail-so-email-attachments-api-openapi.yml
- aid: hail-so:hail-so-email-domains-api
  name: Hail Email Domains API
  description: The email-domains API from Hail — 5 operation(s) for email-domains.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Email Domains
  tags_raw:
  - email-domains
  properties:
  - type: OpenAPI
    url: openapi/hail-so-email-domains-api-openapi.yml
  - type: JSONSchema
    url: json-schema/hail-so-email-domain-response-schema.json
- aid: hail-so:hail-so-emails-api
  name: Hail Emails API
  description: The emails API from Hail — 8 operation(s) for emails.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Email
  tags_raw:
  - emails
  properties:
  - type: OpenAPI
    url: openapi/hail-so-emails-api-openapi.yml
  - type: JSONSchema
    url: json-schema/hail-so-email-response-schema.json
  - type: JSONSchema
    url: json-schema/hail-so-email-create-schema.json
- aid: hail-so:hail-so-events-api
  name: Hail Events API
  description: The events API from Hail — 1 operation(s) for events.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Event
  tags_raw:
  - events
  properties:
  - type: OpenAPI
    url: openapi/hail-so-events-api-openapi.yml
- aid: hail-so:hail-so-forward-targets-api
  name: Hail Forward Targets API
  description: The forward-targets API from Hail — 2 operation(s) for forward-targets.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - forward-targets
  properties:
  - type: OpenAPI
    url: openapi/hail-so-forward-targets-api-openapi.yml
- aid: hail-so:hail-so-healthz-api
  name: Hail Healthz API
  description: The Healthz API from Hail — 1 operation(s) for healthz.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Healthz
  properties:
  - type: OpenAPI
    url: openapi/hail-so-healthz-api-openapi.yml
- aid: hail-so:hail-so-numbers-api
  name: Hail Numbers API
  description: The numbers API from Hail — 6 operation(s) for numbers.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Numbers
  tags_raw:
  - numbers
  properties:
  - type: OpenAPI
    url: openapi/hail-so-numbers-api-openapi.yml
- aid: hail-so:hail-so-providers-api
  name: Hail Providers API
  description: The providers API from Hail — 5 operation(s) for providers.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Providers
  tags_raw:
  - providers
  properties:
  - type: OpenAPI
    url: openapi/hail-so-providers-api-openapi.yml
- aid: hail-so:hail-so-sms-api
  name: Hail Sms API
  description: The sms API from Hail — 5 operation(s) for sms.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - SMS
  tags_raw:
  - sms
  properties:
  - type: OpenAPI
    url: openapi/hail-so-sms-api-openapi.yml
- aid: hail-so:hail-so-unsubscribe-api
  name: Hail Unsubscribe API
  description: The unsubscribe API from Hail — 1 operation(s) for unsubscribe.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Unsubscribe
  tags_raw:
  - unsubscribe
  properties:
  - type: OpenAPI
    url: openapi/hail-so-unsubscribe-api-openapi.yml
- aid: hail-so:hail-so-uploads-api
  name: Hail Uploads API
  description: The uploads API from Hail — 2 operation(s) for uploads.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Uploads
  tags_raw:
  - uploads
  properties:
  - type: OpenAPI
    url: openapi/hail-so-uploads-api-openapi.yml
- aid: hail-so:hail-so-verifications-api
  name: Hail Verifications API
  description: The verifications API from Hail — 9 operation(s) for verifications.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Verification
  tags_raw:
  - verifications
  properties:
  - type: OpenAPI
    url: openapi/hail-so-verifications-api-openapi.yml
  - type: JSONSchema
    url: json-schema/hail-so-verification-response-schema.json
- aid: hail-so:hail-so-webhooks-api
  name: Hail Webhooks API
  description: The webhooks API from Hail — 6 operation(s) for webhooks.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Webhook
  tags_raw:
  - webhooks
  properties:
  - type: OpenAPI
    url: openapi/hail-so-webhooks-api-openapi.yml
- aid: hail-so:hail-so-whoami-api
  name: Hail Whoami API
  description: The whoami API from Hail — 1 operation(s) for whoami.
  humanURL: https://hail.so/docs/api
  baseURL: https://api.hail.so
  tags:
  - Whoami
  tags_raw:
  - whoami
  properties:
  - type: OpenAPI
    url: openapi/hail-so-whoami-api-openapi.yml
x-enrichment:
  date: '2026-11-11'
  status: enriched
  artifacts_added: 33
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Hail API — frequently asked questions

Does Hail have an API?

Yes. APIs.io lists 17 APIs from Hail, including Hail Agents API, Hail Calls API and Hail Contacts API, and 14 more.

Is there an OpenAPI specification for the Hail API?

Yes. APIs.io indexes 17 OpenAPI specifications for Hail, each linked for download from this page.

Is the Hail API ready for AI agents?

Hail has a Kin Score of 43.7 out of 100 (developing) and an Agent Readiness score of 52.2 (agent-native), scored by API Evangelist on 2026-11-13.

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This provider

curl "https://apis.io/api/v1/providers/hail-so"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/hail-so/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/hail-so/evidence"

Calls without X-API-Key need no key. Calls with it need a paid plan — get a key.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.