Install Jentic One Beta

Connect the PenPals API to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the PenPals API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.

Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.

Step 1: Jentic One Host machine

# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fpenpalsapp.com%2Fpenpals" | sh

Step 2: Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fpenpalsapp.com%2Fpenpals" | sh
jentic register       # connects your agent to your Jentic One instance

Jentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.

Capabilities

What an agent can do with PenPals API.

Create handwritten letter orders from natural language descriptions via a concierge endpoint

Manage recipient addresses individually or in bulk for mail campaigns

Design letter templates with custom font and ink color selections

Process cart items through to completed orders with cost calculation

Browse product categories and extras for handwritten mail customization

GET STARTED

Start building with PenPals API

Explore with Jentic One

View OpenAPI Document

Use Cases

Patterns agents use PenPals API for, with concrete tasks.

★ Automated Handwritten Mail Campaigns

Send personalized handwritten letters at scale by managing addresses in bulk and creating orders programmatically. The API supports bulk address creation (POST /api/v1/addresses/bulk), template management with custom fonts and ink colors, and order processing. Agents can orchestrate campaigns that feel personal while operating at marketing scale.

Create 5 addresses via POST /api/v1/addresses/bulk, select a template with a cursive font, add items to cart via POST /api/v1/cart, then create an order via POST /api/v1/orders/create

Natural Language Order Creation

Create handwritten letter orders from plain-text descriptions using the concierge endpoint. POST /api/v1/orders/concierge accepts natural language input and produces a structured order, reducing the steps needed to go from idea to physical mail. This enables chatbot and agent-driven order flows without explicit template or product selection.

Submit a natural language description to POST /api/v1/orders/concierge: 'Send a thank-you letter to John at 123 Main St in blue ink with a friendly tone'

Template Library Management

Build and manage a library of reusable letter templates with specific fonts, ink colors, and content layouts. The API provides GET /api/v1/templates/fonts for available fonts, GET /api/v1/templates/ink-colors for color options, and full CRUD on templates. Agents can maintain branded template collections for different customer communication scenarios.

Retrieve available fonts via GET /api/v1/templates/fonts, select a script font, then create a template via POST /api/v1/templates with the chosen font and blue ink color

AI Agent Mail Operations via Jentic

AI agents discover and execute PenPals operations through Jentic to send handwritten mail without building a custom integration. Agents search for mail capabilities by intent, receive typed operation schemas, and create orders or manage templates through Jentic's unified interface. OAuth token handling and endpoint discovery are managed automatically.

Search Jentic for 'send a handwritten letter', load the POST /api/v1/orders/concierge schema, and execute with a natural language order description

Key Endpoints

45 endpoints — jentic publishes the only available openapi specification for penpals api, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/api/v1/orders/concierge

Create order from natural language

POST

/api/v1/orders/create

Create a new order

POST

/api/v1/orders/calculate

Calculate order cost

POST

/api/v1/addresses/bulk

Create multiple addresses

GET

/api/v1/products

List all products

POST

/api/v1/templates

Create a letter template

GET

/api/v1/templates/fonts

List available fonts

POST

/api/v1/cart

Add item to cart

POST

/api/v1/orders/concierge

Create order from natural language

POST

/api/v1/orders/create

Create a new order

POST

/api/v1/orders/calculate

Calculate order cost

POST

/api/v1/addresses/bulk

Create multiple addresses

GET

/api/v1/products

List all products

POST

/api/v1/templates

Create a letter template

GET

/api/v1/templates/fonts

List available fonts

POST

/api/v1/cart

Add item to cart

Why Jentic?

What agents get from Jentic-routed access to this vendor.

Setup

Wiring PenPals by hand means managing its JWT bearer tokens and their refresh lifecycle and assembling order, address, and template payloads for handwritten mail yourself. Through Jentic you install once, import the PenPals API from the API Directory, store the token once, and your agent calls it while refresh is handled for you.

Permission scoping

PenPals takes its order details in the request body across endpoints like /api/v1/orders/create and /api/v1/orders/concierge, so scoping is operations-only: limit the agent to the operations it needs, such as calculating and creating an order, and leave bulk address upload or template creation out of the allowed set unless you add them.

Credential isolation

Your PenPals bearer token is stored once, encrypted, by your own Jentic One instance and injected at execution time, with refresh handled automatically. It never enters the agent's prompt, logs, or context.

Intent-based discovery

Agents search Jentic by intent such as 'send a handwritten letter', and Jentic returns the matching PenPals operation, including the natural-language concierge endpoint, with its input schema so the agent calls the right endpoint without browsing the reference docs.

FAQs

Specific to using PenPals API through Jentic.

Why is there no official OpenAPI spec for PenPals API?

PenPals does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call PenPals API via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.

What authentication does the PenPals API use?

The PenPals API uses Bearer token authentication with JWT format. Obtain a token via POST /api/v1/auth/token using OAuth 2.0 credentials. Through Jentic, token acquisition and refresh are handled automatically so agents do not manage the auth flow directly.

Can I create orders from natural language descriptions?

Yes. POST /api/v1/orders/concierge accepts a natural language description and produces a structured order. This endpoint handles product selection, address parsing, and template matching from plain-text input, enabling conversational order creation.

How do I manage addresses in bulk through Jentic?

Search Jentic for 'create multiple recipient addresses' to discover the POST /api/v1/addresses/bulk endpoint. Load the operation schema and execute with an array of address objects. The API also supports PATCH /api/v1/addresses/bulk for bulk updates and DELETE /api/v1/addresses/bulk for removal.

What fonts and ink colors are available for templates?

GET /api/v1/templates/fonts returns all available handwriting fonts, and GET /api/v1/templates/ink-colors returns the available ink color options. Use these values when creating templates via POST /api/v1/templates to specify the visual style of letters.

Can I calculate order costs before submitting?

Yes. POST /api/v1/orders/calculate accepts the same payload as order creation and returns the total cost breakdown without actually creating the order. This enables cost preview and approval workflows before committing to physical mail production.

Can I limit what my agent is allowed to do with the PenPals API?

Yes. Because you run Jentic One yourself, your own rules decide which PenPals operations and credentials the agent may use, so you allow only the endpoints it needs. For example, you can permit calculating and creating an order (POST /api/v1/orders/calculate and POST /api/v1/orders/create or the concierge endpoint) while leaving bulk address upload (POST /api/v1/addresses/bulk) and template creation (POST /api/v1/templates) out of the allowed set. Scoping is operations-based, since PenPals passes order details in the request body, and the stored bearer token is injected only when a permitted operation runs.

Penpalsapp PenPals API

Name: PenPals API
Brand: PenPals API
Availability: InStock

AI ReadinessFoundational (D+)49/100

See full scorecard

Agent-ready OpenAPI document · curated by JenticE CommerceOrder Managementbearer45 EndpointsREST

Know of an official OpenAPI document? Contribute it →

For Agents

Create and manage handwritten letter orders including addresses, cart items, templates with custom fonts and ink colors, and order processing. Supports natural language order creation via a concierge endpoint.

Use for: I need to create a handwritten letter order, List all available fonts for letter templates, I want to add items to the cart for bulk mailing, Calculate the total cost for an order before submitting

Not supported: Does not handle digital messaging, email delivery, or SMS - use for physical handwritten mail and postcard orders only.

Jentic publishes the only available OpenAPI specification for PenPals API, keeping it validated and agent-ready. PenPals API powers a handwritten letter and postcard marketplace with 45 endpoints covering addresses, cart management, orders, products, templates, and authentication. It supports creating orders from natural language via a concierge endpoint, managing handwritten letter templates with custom fonts and ink colors, and processing orders for physical mail delivery.

Jentic One on Github View OpenAPI Document

Show dimension breakdown

Foundational Compliance

Base layer of spec validity and structural soundness.

Grade: A-Signals: 4

96%

Lint Results

Aggregated quality score from linter diagnostics, weighted by severity.

100%

Resolution Completeness

Percentage of `$ref` references that resolve successfully.

100%

Specification Validity

Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).

Structural Integrity

Structural correctness score based on schema issues using logarithmic dampening.

Developer Experience & Jentic Compatibility

Clarity, completeness, and ingestion readiness for developers and tooling.

Grade: BSignals: 4

13%

Example Density

How richly the API is illustrated with examples.

97%

Example Validity

Percentage of examples that conform to their schemas.

49%

Response Coverage

Percentage of operations with complete response definitions (success, client error, server error).

100%

Tooling Readiness

Health of API ingestion, bundling, and resolution within Jentic pipelines.

AI-Readiness & Agent Experience

Semantic breadth, depth, and agent comprehension for AI systems.

Grade: FSignals: 4

29%

Description Coverage

Coverage of descriptions across API elements.

Error Standardization

Coverage of RFC 9457 Problem Details for error responses.

OperationId Quality

Coverage, uniqueness, and casing consistency of operationIds for AI inference.

60%

Summary Coverage

Coverage of summaries across operations/tags/info.

Agent Usability

Functional utility, complexity comfort, and AI orchestration readiness.

Grade: A+Signals: 1

94%

Complexity Comfort

Agent comfort level based on API operational and structural complexity.

Security

Trust, risk posture, and security compliance.

Grade: A-Signals: 1

75%

Authentication Strength

Average quality of security schemes based on authentication method strength (weakest link for OAuth2).

AI Discoverability

Findability, semantic richness, and reasoning readiness.

Grade: ASignals: 1

80%

Descriptive Richness

Clarity and depth of descriptions across API elements.

Connect the PenPals API to your agent

Capabilities

Start building with PenPals API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs

Penpalsapp PenPals API

Jentic AI Readiness Score

PenPals API

Foundational Compliance

Lint Results

Resolution Completeness

Specification Validity

Structural Integrity

Developer Experience & Jentic Compatibility

Example Density

Example Validity

Response Coverage

Tooling Readiness

AI-Readiness & Agent Experience

Description Coverage

Error Standardization

OperationId Quality

Summary Coverage

Agent Usability

Complexity Comfort

Security

Authentication Strength

AI Discoverability

Descriptive Richness