# Claude

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> Claude is Anthropic's family of AI models and its assistant. How Claude reads the web, which agents fetch your pages, and why its answers about you vary.

- Canonical page: https://attensira.com/glossary/claude
- Family: glossary
- Last updated: 2026-10-04
- Author: Karl-Gustav Kallasmaa (https://attensira.com/about)
- Claims as data: https://attensira.com/claims.json?slug=claude

**In short:** Claude is Anthropic's family of large language models and the AI assistant built on them. It answers from what a model learned in training, up to that model's knowledge cutoff, and can search and fetch web pages at answer time through Anthropic's own agents. Which model answers, and whether it searched, changes what Claude can say about you.

**Perplexity, asked 2026-10-03:** "track brand mentions in ChatGPT, Claude and Perplexity"

> Brand mentions across ChatGPT, Claude, and Perplexity: there is no single official, universal tracker; most methods rely on running targeted prompts across each platform multiple times, recording whether your brand is mentioned, cited, or described, and noting sentiment, position, and context.

Sources cited, in order: frictionai.co, brandpul.se, trysight.ai, 01net.com, seoforgpt.io, how2shout.com.

Attensira: not named.

_Source: attensira.com workspace, read over the Attensira MCP, as of 2026-10-04 (n=12 answers to this question, Attensira named in 0)._

## Key facts

- Made by: [Anthropic](/glossary/anthropic)
- What it is: A family of models plus the claude.ai assistant
- Fetches pages with: ClaudeBot, Claude-SearchBot, Claude-User
- Knows after its cutoff: [Only what it fetches at answer time](/glossary/knowledge-cutoff)
- In Attensira: [A default channel, read over the API](https://docs.attensira.com/tracking/models)
- In our own workspace: Not read: we track ChatGPT and Perplexity

## What does Claude read from a website?

Two different things, depending on when you ask. Claude answers from training up to the model's knowledge cutoff, and from pages Anthropic's agents fetch at answer time. Each agent leaves a different trace in your log and answers to a different robots.txt rule:

| Agent | What it is for | What a visit tells you |
| --- | --- | --- |
| Claude-User | a person asked Claude something and it opened your page | Claude used your page in a live answer, there and then |
| Claude-SearchBot | building Claude's search results | your page can be found when Claude searches |
| ClaudeBot | collecting content that may contribute to training | your page may shape a future model, not today's answer |

Claude-User is the row to watch. It is the most direct evidence a log can give that Claude read you for a real question. Our own totals for attensira.com, including the share that was Claude-User, are on [Anthropic](/glossary/anthropic#what-does-anthropic-fetch-from-a-website); further down this page are the pages it opened.

Our workspace reads ChatGPT and Perplexity answers, not Claude's, so this page quotes no Claude answer rate; a number we did not measure is not zero. The answer at the top of this page is Perplexity's, to a question about tracking Claude. It describes the method fairly: run the same questions on each assistant many times and record what comes back.

## What is Claude?

Claude is Anthropic's family of large language models and the assistant built on them. Anthropic's [models overview](https://platform.claude.com/docs/en/about-claude/models/overview) calls it a family, and the plural matters. As read on 4 October 2026:

| Model | Context window | Reliable knowledge cutoff |
| --- | --- | --- |
| Claude Fable 5.1 | 1M tokens | Jun 2026 |
| Claude Opus 5.5 | 1M tokens | Jun 2026 |
| Claude Sonnet 5.5 | 1M tokens | Jun 2026 |
| Claude Haiku 4.5 | 200K tokens | Feb 2025 |

Older models remain available too. Anthropic notes 1M tokens is roughly 555k words on its current tokenizer. This lineup changes; the page you are reading had a different one a month earlier.

Two of these properties change what Claude can say about you:

- **Knowledge cutoff.** What a model knows without searching stops at its [cutoff](/glossary/knowledge-cutoff). A rebrand, a new product or a price change after that date does not exist in its memory.

- **Context window.** How much text it can read at once. Even a million tokens is finite against the web, so something still chooses which passages enter. See [context window](/glossary/context-window).

## How does Claude use the web?

When Claude searches, it does [retrieval-augmented generation](/glossary/rag): it fetches pages, puts selected passages into its context and writes from them, citing what it used. That is [grounding](/glossary/grounding), and it is the only way anything published after a model's cutoff reaches an answer.

It depends on Anthropic's agents being able to fetch you. Anthropic [documents](https://support.claude.com/en/articles/8896518-does-anthropic-crawl-data-from-the-web-and-how-can-site-owners-block-the-crawler) three, each controlled separately in [robots.txt](/glossary/robots-txt): ClaudeBot for training, Claude-SearchBot for search, and Claude-User for fetches a person triggers. Anthropic publishes the IP ranges they use at `claude.com/crawling/bots.json`, so a log entry can be verified rather than trusted.

## Which of our pages did Claude open for a real question?

Claude-User is the agent that fetches a page because a person asked Claude something. In 30 days it was seen on 19 of our 30 most-fetched pages; three are shown. On /about and /use-cases/saas-startups (a page since removed) it was the only Anthropic agent seen: by the user agent each request claimed, these were fetches a person triggered, not crawls (none IP-verified).

**Three of 19 top-30 pages where Claude-User was seen, 5 Sep to 4 Oct 2026**

| Page | Fetches by all AI agents | Anthropic agents seen |
| --- | --- | --- |
| /about | 7,710 | Claude-User |
| /mcp | 4,142 | Claude-User, ClaudeBot |
| /use-cases/saas-startups (page since removed) | 3,799 | Claude-User |

_Source: attensira.com AI-crawler log, read over the Attensira MCP, as of 2026-10-04 (n=143,601 AI-crawler requests)._

## Why do Claude's answers about you vary?

Because "what does Claude say about us" is several questions at once:

- **Which model answered.** A smaller, older model and a newer one have different cutoffs and different knowledge of you.

- **Whether it searched.** An answer from memory and an answer grounded in your current pages can disagree.

- **Run to run.** Language models are not deterministic; the same question asked twice can be answered differently.

So one Claude answer is one observation. Read many before concluding anything.

## What are the common mistakes about Claude?

**A blanket block.** A rule naming every Anthropic agent, or a broad wildcard, can reduce your visibility in Claude's answers as a side effect of a training decision.

**Reading a stale answer as a hallucination.** A model that never saw your rebrand will describe the old brand confidently. It is correctly recalling an old fact. The fix is making the new fact fetchable. See [AI hallucination](/glossary/ai-hallucination).

**Assuming a citation validates the sentence.** Retrieval and writing fail separately; a correct link can sit under a wrong summary.

**Writing pages, not passages.** Claude selects sections. A claim whose qualifier lives three paragraphs away arrives without it.

## How does Attensira track Claude?

Claude is one of the engines Attensira can read every day: it asks your buyers' questions, stores Claude's answers verbatim, and records whether you are named and linked, with the sample size. Its [crawler logs](/features/crawler-logs) show which Anthropic agents fetched which pages, and [model tracking](/features/models) explains which assistants a plan reads. The crew then fixes access and passages and ships each change after your approval. The [free audit](/audit) asks Claude eight questions about your category and shows whether it named you.

## FAQ

### What is Claude?

Claude is the family of large language models built by Anthropic, and the assistant at claude.ai built on them. Anthropic's documentation describes it as a family of state-of-the-art models rather than a single system, so which Claude model answered matters.

### Is Claude one model or several?

Several. Anthropic's models overview, as read on 4 October 2026, listed Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5 and Claude Haiku 4.5 as the current lineup, with older models still available. They differ in speed, context window and knowledge cutoff.

### How large is Claude's context window?

It depends on the model. On 4 October 2026 Anthropic listed 1M tokens for Fable 5.1, Opus 5.5 and Sonnet 5.5 and 200K tokens for Haiku 4.5, noting that 1M tokens is roughly 555k words on the current tokenizer.

### Does Claude know about my page if it was published after the training cutoff?

Not from training. Anthropic publishes a reliable knowledge cutoff per model, June 2026 for the larger current models and February 2025 for Haiku 4.5 as of October 2026. Anything newer reaches Claude only if it is fetched at answer time.

### Which Anthropic agents fetch my pages?

Three. ClaudeBot collects content that may contribute to training, Claude-SearchBot crawls to improve search results, and Claude-User fetches a page when a person asks Claude something. Blocking ClaudeBot is a training decision; Anthropic says blocking the other two can reduce your visibility in Claude's answers.