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Overview

ABP uses dot-notation namespaces to organize capabilities:
Examples:
  • export.pdf — Export as PDF
  • convert.markdownToHtml — Convert markdown to HTML
  • ai.summarize — Summarize text using AI
  • render.html — Render HTML with CSS

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Standard Namespaces

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export.* — Export Operations

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convert.* — Format Conversion

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render.* — Rendering Operations

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ai.* — AI Operations

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storage.* — Browser Storage

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auth.* — Authentication

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Forbidden Capabilities: Delivery and Input-Acquisition Mechanisms

Apps MUST NOT declare capabilities that wrap browser delivery mechanisms or input-acquisition APIs. These are browser features that route content to an OS-level destination (clipboard, share sheet, file dialog, notification) or acquire input through OS-level UI (file picker, camera prompt). An ABP capability should produce or consume data — the agent handles routing and acquisition on the host side.
For a decision test to identify these mechanisms, see the Implementation Guide — How to Recognize a Delivery Mechanism. The primary example is clipboard.*: apps MUST NOT declare clipboard.* capabilities. The browser Clipboard API requires user gestures that automated agents cannot provide, and clipboard is a host-side delivery mechanism — agents can write to the system clipboard directly using host tools (pbcopy, xclip, clip). Instead, expose the underlying content-producing capability (e.g., convert.markdownToHtml) and let the agent handle clipboard operations on the host side. The same principle applies to navigator.share(), showSaveFilePicker() / showOpenFilePicker(), new Notification(), and any future browser API that triggers OS-level UI. See the Protocol Overview for additional context on forbidden capabilities.

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Vendor Namespaces

Vendors can use reverse-domain notation for custom capabilities:
Examples:
  • com.acme.imageFilter.blur
  • io.github.username.customTool

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Naming Conventions

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Action Verbs

Use consistent action verbs:
  • Create/Generate: export.pdf, generate.thumbnail
  • Read/Get: storage.read, auth.getToken
  • Write/Set: storage.write, storage.set
  • Convert/Transform: convert.markdownToHtml
  • Delete/Remove: storage.delete

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Case Convention

  • Use camelCase for multi-word names
  • Namespace and action are separated by .
  • Examples: convert.markdownToHtml, auth.getToken

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Capability Lifecycle

Capabilities progress through three stages:

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Experimental

  • Marked with experimental: true in the manifest
  • May change without notice between versions
  • Agents SHOULD warn users when calling experimental capabilities

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Stable

  • The default state (no experimental or deprecated flag)
  • Follow semantic versioning
  • Breaking changes only in major protocol versions

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Deprecated

  • Marked with deprecated: true and optionally deprecationMessage
  • Deprecated capabilities MUST remain functional for at least one major version
  • The alternatives field SHOULD suggest replacement capabilities
  • Agents SHOULD warn users when calling deprecated capabilities
See the Protocol Overview for the full lifecycle details.

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Next Steps

Examples & Tutorials

See capabilities in action

Building ABP Apps

Build your own app with capabilities

Protocol Overview

Full specification details