Glossary
The terms behind AI agents, browsers and websites, each defined in a few sentences.
Agents & MCP
AI agentAn AI agent is a system where a language model repeatedly picks actions, calls tools, reads the results and continues until a goal is met.Browser agentA browser agent is an AI agent that operates a web browser, reading each page and clicking, typing and navigating one step at a time with model calls.Computer useComputer use: a model capability where the model views screenshots and issues mouse and keyboard actions to control a computer or browser.MCP clientAn MCP client is the part of an AI app that holds a connection to one MCP server, lists its tools and forwards the model's tool calls to it.MCP serverAn MCP server is a program that exposes tools, resources and prompts to an MCP client over JSON-RPC 2.0. Wield's wield-mcp is a local MCP server.MCPB bundle (.mcpb)An MCPB bundle is a zip archive with a manifest.json that packages a local MCP server so a desktop app can install it with one click. Formerly called DXT.Model Context Protocol (MCP)MCP is an open protocol that lets AI apps like Claude, Cursor and Codex call external tools and read data through small servers, local or remote.stdio transportstdio transport is an MCP transport where the client starts the server as a subprocess and exchanges JSON-RPC messages over standard input and output.Streamable HTTPStreamable HTTP is an MCP transport where the server exposes one HTTP endpoint that accepts JSON-RPC messages by POST, with optional Server-Sent Events.Tool callingTool calling is a model capability where the model outputs a tool name and JSON arguments, and the application runs the tool and returns the result.
Bot protection
Akamai Bot ManagerAkamai Bot Manager is a commercial Akamai product. It classifies traffic as human, known bot or unknown automation, then allows, challenges or blocks it.AWS WAFAWS WAF is Amazon's web application firewall. It filters HTTP requests with rules and can issue CAPTCHA or silent Challenge actions, plus Bot Control.Browser fingerprintingBrowser fingerprinting identifies a browser by combining many attributes, such as headers, fonts and hardware signals, without cookies.CAPTCHAA CAPTCHA is a test that tells humans from automated programs. Sites use it as a visible check, and Wield stops and asks the user to solve it.Cloudflare TurnstileTurnstile is Cloudflare's CAPTCHA alternative. It verifies visitors with light challenges and returns a token the site checks on its server.PerimeterX / HUMANPerimeterX, a bot-defence vendor, was acquired by HUMAN Security in 2022 and is now sold as HUMAN Bot Defender. Its best-known check is press-and-hold.
Browsers
Chrome DevTools Protocol (CDP)Chrome DevTools Protocol (CDP): a JSON protocol over WebSocket that tools use to inspect, debug and control Chromium browsers.Content scriptContent script: JavaScript an extension injects into web pages. It reads and changes the page DOM in an isolated world, apart from the page's own scripts.Extension service workerExtension service worker: the event-driven background script of a Manifest V3 extension. It starts when an event fires and stops when it sits idle.Headless browserHeadless browser: a web browser with no visible window, driven by a program through Chrome DevTools Protocol or WebDriver.Manifest V3Manifest V3: the current Chrome extension platform, with a version 3 manifest, service-worker background scripts and no remote code.Native messagingNative messaging: a Chrome extension feature that exchanges JSON messages with a native app on the user's computer over stdin and stdout, with no network port.
Concepts
Local-first softwareLocal-first software keeps the main copy of your data on your device, works offline and treats servers as secondary, as defined in the 2019 Ink & Switch essay.Recipe (Wield)A Wield recipe is a small, public, signed JSON file that describes the requests a website's own pages make. The Wield extension runs it in your browser.Site challengeA site challenge is a check, such as a CAPTCHA or an are you human page, that a website shows to confirm a visitor is human and that stops automated access.Web scrapingWeb scraping means extracting data from websites by fetching pages or their backing requests and parsing the result. Wield recipes work differently.
Security
Audit logAn audit log is a chronological record of actions in a system, kept to review who did what and when. Wield keeps its logs on the user's computer.Ed25519 signaturesEd25519 is a public-key signature scheme on Curve25519 (EdDSA, RFC 8032). Signatures are 64 bytes, and clients use them to verify recipes.Human-in-the-loopHuman-in-the-loop means a person must approve certain AI agent actions before they run. It is the main control for actions that cannot be undone.Least privilegeLeast privilege means a component holds only the access its task needs. For AI agents, it limits what a mistake or injected instruction can do.Prompt injectionPrompt injection is an attack where text in data an AI model reads, such as a web page or email, contains instructions the model wrongly follows.
Web data
__NEXT_DATA____NEXT_DATA__ is a script tag on Next.js Pages Router sites. It holds the server-rendered page props as JSON, which tools can read directly.Bearer tokenA bearer token is a credential sent in an Authorization: Bearer header. Whoever holds the token can use it, so keep it secret (RFC 6750).Cookies and sessionsA cookie is a small name-value pair the browser returns on later requests. A session cookie keeps a user logged in, so whoever holds it can act as them.CORSCORS (Cross-Origin Resource Sharing) is an HTTP header rule that lets a server tell browsers which other sites may read its responses.CSRF tokenA CSRF token is a secret value a site checks on requests that change data. It blocks forged requests that ride on the user's cookies.CSS selectorA CSS selector matches HTML elements by tag, class, id, attribute or position. Wield recipes use selectors to read data that exists only in a page's HTML.GraphQL persisted queryA GraphQL persisted query is a stored server-side query that a client calls by ID or hash instead of sending the full text.HAR fileA HAR file is an HTTP Archive: JSON that records a browser's network requests and responses, exported from DevTools. Raw HARs can hold cookies and tokens.Internal APIAn internal API is an HTTP endpoint that a website's own pages call. It is usually undocumented, so it can change without notice.JMESPathJMESPath is a query language for JSON. Expressions such as people[?age>`20`].name pull and reshape values. Wield recipes use it to read responses.JSON SchemaJSON Schema is a vocabulary for describing and validating JSON, with keywords such as type, properties and required. MCP tools use it to declare their inputs.Rate limitingRate limiting caps how many requests a client can send in a time window. Servers often answer 429 Too Many Requests, sometimes with Retry-After.Same-origin policySame-origin policy: a browser rule that limits how a script from one origin (scheme, host and port) can read responses from another origin.Server-side rendering (SSR)Server-side rendering (SSR) builds a page's HTML on the server for each request, so its content arrives in the first response.