> ## Documentation Index > Fetch the complete documentation index at: https://agenticbrowserprotocol.io/llms.txt > Use this file to discover all available pages before exploring further. # Conformance Requirements > Minimum requirements for ABP-compliant apps and clients Minimum requirements for ABP-compliant apps and clients. ## Overview This document defines the minimum requirements for ABP conformance. Use this as a checklist before implementing or shipping ABP support. **Key words:** The terms **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **MAY**, and **OPTIONAL** are defined in [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt). In brief: * **MUST** / **REQUIRED** -- An absolute requirement. Implementations that fail this are non-conformant. * **SHOULD** / **RECOMMENDED** -- There may be valid reasons to ignore this in particular circumstances, but the implications must be understood. * **MAY** / **OPTIONAL** -- Truly optional. Implementations may or may not include this. ## App Conformance ### Required (MUST) An ABP-compliant web application **MUST**: Include `` in the HTML ``. See [Discovery Guide](/concepts/discovery). A JSON file with `abp`, `app` (containing `id`, `name`, `version`), and `capabilities` fields. See [Discovery Guide](/concepts/discovery#manifest-format). An object on the global `window` implementing the ABP interface. See [API Reference](/reference/api). Accept agent identification and return session info with capabilities. See [Protocol Overview](/concepts/protocol-overview#session-lifecycle). Clean up session resources. See [API Reference](/reference/api#shutdown). Execute capabilities and return `ABPResponse` with `success`, `data` or `error`. See [API Reference](/reference/api#call). Every capability MUST produce its declared output in the `ABPResponse`. Capabilities MUST NOT return status messages describing side effects (e.g., "print dialog opened") instead of actual output. See [Common Pitfalls: Status Messages](/guides/common-pitfalls#anti-pattern-status-messages-instead-of-data). Capabilities MUST NOT call `alert()`, `confirm()`, `prompt()`, `window.open()`, or trigger programmatic downloads. `window.print()` is allowed only as a transport signal for PDF generation. See [Common Pitfalls: Native Browser UI](/guides/common-pitfalls#anti-pattern-native-browser-ui). Deprecated capabilities MUST remain functional for at least one major version before removal. See [Capability Taxonomy](/concepts/capabilities#capability-lifecycle). ### Recommended (SHOULD) An ABP-compliant web application **SHOULD**: 1. **Implement `listCapabilities()`** and **`supports()`** for runtime discovery * Allows agents to query capabilities dynamically * See [API Reference](/reference/api#discovery-methods) 2. **Support notifications** via `notify()` and `notifyProgress()` * Enables real-time updates to agents * See [Elicitation & Progress](/concepts/elicitation-and-progress) 3. **Support elicitation** via `elicit()` for requesting input from agents * Allows capabilities to ask for user preferences or confirmation * See [Elicitation & Progress](/concepts/elicitation-and-progress#elicitation) 4. **Validate inputs** against declared `inputSchema` before executing capabilities * Prevents invalid data from causing errors * See [Building ABP Apps: Parameter Validation](/guides/building-web-apps#pattern-parameter-validation) 5. **Declare requirements** for permission-gated capabilities * Lets agents know what conditions must be met * See [Security Considerations](/concepts/security#permission-model) ## Client Conformance ### Required (MUST) An ABP-compliant client implementation **MUST**: Fetch HTML ``, parse the `` tag, and fetch the manifest JSON. See [Discovery Guide](/concepts/discovery). Call `window.abp.initialize()` with agent identification and feature flags. See [Protocol Overview](/concepts/protocol-overview#initialize). Use `window.abp.call()` and handle `ABPResponse` (check `success`, read `data` or `error`). See [API Reference](/reference/api#call). Call `window.abp.shutdown()` when done. See [Protocol Overview](/concepts/protocol-overview#shutdown). Client implementations using Puppeteer/Playwright MUST use these function names for interoperability: `__abp_notification`, `__abp_progress`, `__abp_elicitation`, `__abp_capabilities_changed`. See [API Reference](/reference/api#puppeteer-callback-function-names). Clients MUST NOT trust manifest capabilities without runtime verification via `initialize()`. See [Security Considerations](/concepts/security#5-manifest-security). Clients MUST NOT execute code or scripts referenced in manifests. See [Security Considerations](/concepts/security#5-manifest-security). Clients MUST NOT grant permissions based solely on manifest claims. See [Security Considerations](/concepts/security#5-manifest-security). ### Recommended (SHOULD) An ABP-compliant client implementation **SHOULD**: 1. **Support both headless and headful browser modes** when using Puppeteer/Playwright * Some capabilities require a visible browser (authenticated sessions, GPU, permissions) * Default to headless; allow headful as an option * See [Architecture Guide: Browser Requirements](/concepts/architecture#browser-requirements) 2. **Handle notifications** -- Set up `page.exposeFunction()` for `__abp_notification` and `__abp_progress` * See [Architecture Guide](/concepts/architecture#bidirectional-communication) 3. **Handle elicitation** -- Set up `page.exposeFunction()` for `__abp_elicitation` to respond to app requests * See [Elicitation & Progress](/concepts/elicitation-and-progress) 4. **Handle binary data** -- Process `BinaryData` and `BinaryDataReference` responses * See [Binary Data Protocol](/reference/binary-data) 5. **Handle errors** -- Implement retry logic for retryable errors with exponential backoff * See [Error Handling](/reference/error-handling) 6. **Handle version mismatches gracefully** -- Agents SHOULD handle manifest protocol version mismatches according to the version compatibility rules * See [Discovery Guide](/concepts/discovery#version-compatibility) ## Verification ### Verifying App Conformance **Manual test in browser console:** ```javascript theme={null} // 1. Check window.abp exists console.log(window.abp); // Should be an object, not undefined // 2. Check required methods exist console.log(typeof window.abp.initialize); // "function" console.log(typeof window.abp.shutdown); // "function" console.log(typeof window.abp.call); // "function" // 3. Test initialization const session = await window.abp.initialize({ agent: { name: 'test', version: '1.0' }, protocolVersion: '0.1', features: { notifications: false, progress: false, elicitation: false } }); console.log('Session:', session); // Should have sessionId, app, capabilities // 4. Test capability call const result = await window.abp.call('convert.markdownToHtml', { markdown: '# Hello ABP', options: { sanitize: true } }); console.log('Result:', result); // Should have success: true, data: { ... } // 5. Verify data, not status message console.log('Has actual data?', result.data && typeof result.data === 'object'); console.log('Not a status message?', !result.data?.status && !result.data?.message); // 6. Test shutdown await window.abp.shutdown(); console.log('Shutdown complete'); ``` **Automated test with MCP Bridge:** ```bash theme={null} # Connect to your app abp_connect("http://localhost:3000") # Should succeed and show available capabilities # Then test a capability: abp_call("convert.markdownToHtml", {"markdown": "# Test", "options": {"sanitize": true}}) # Should return actual data, not a status message ``` ### Verifying Client Conformance 1. **Discovery test:** ```javascript theme={null} const discovery = await discoverABP('https://app.example.com'); console.assert(discovery.supported === true); console.assert(discovery.manifest.abp === '1.0'); ``` 2. **Session lifecycle test:** ```javascript theme={null} const session = await client.connect('https://app.example.com'); console.assert(session.sessionId !== null); console.assert(session.capabilities.length > 0); await client.disconnect(); console.assert(session.sessionId === null); ``` 3. **Capability call test:** ```javascript theme={null} const result = await client.call('convert.markdownToHtml', { markdown: '# Test' }); console.assert(result.success === true || result.error !== undefined); ``` ## Common Conformance Failures ### For Apps | Failure | Symptom | Fix | | ------------------------------- | --------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | | No manifest link | Discovery fails | Add `` to `` | | Invalid manifest | "Invalid manifest structure" | Ensure `abp`, `app.id`, `app.name`, `app.version`, `capabilities` fields exist | | `window.abp` undefined | "window\.abp not found" | Load ABP runtime before other scripts | | Status messages instead of data | Calls succeed but return useless output | Return actual data (see [Common Pitfalls](/guides/common-pitfalls#anti-pattern-status-messages-instead-of-data)) | | Native UI calls | Calls hang indefinitely | Remove `alert()`, `confirm()`, `prompt()` (see [Common Pitfalls](/guides/common-pitfalls#anti-pattern-native-browser-ui)) | ### For Clients | Failure | Symptom | Fix | | ----------------------------- | ---------------------------------- | ------------------------------------------------------------------- | | Headless mode | Permission-gated capabilities fail | Use `headless: false` | | Not checking `success` flag | Crashes on error responses | Always check `if (result.success)` | | Not handling retryable errors | Gives up on transient failures | Check `error.retryable` and retry with backoff | | Large data through context | Agent performance degrades | Route large outputs to files (see [Data Flow](/concepts/data-flow)) | ## Next Steps Detailed anti-patterns to avoid Build your first ABP app Build a client implementation Full protocol specification