# Content Signals

> A robots.txt extension that lets a site declare how its content may be used after access — search, ai-input, and ai-train — as machine-readable preferences.

_The Agent Protocol Atlas · /protocols/content-signal · [JSON](/api/protocols/content-signal) · [all The Agent Protocol Atlas](/protocols)_

- **name:** Content Signals
- **full_name:** Cloudflare Content Signals Policy
- **layer:** licensing
- **creator:** Cloudflare
- **status:** live (2025)
- **year:** 2025
- **one_liner:** A robots.txt extension that lets a site declare how its content may be used after access — search, ai-input, and ai-train — as machine-readable preferences.
- **spec_url:** https://blog.cloudflare.com/content-signals-policy/
- **snippet:**

```
# robots.txt
Content-Signal: search=yes, ai-input=yes, ai-train=no
```
- **abbreviation:** Content Signals
- **also_known_as:** Content Signals Policy, Content-Signal
- **canonical_spec_url:** https://contentsignals.org
- **entity_uri:** https://blog.cloudflare.com/content-signals-policy/
- **taxonomy_layer:** licensing
- **sub_layer:** content-use-preferences
- **protocol_type:** declaration
- **central_problem:** Lets a site express, in robots.txt, how crawlers may use its content after access — for search, AI input (RAG/grounding), or AI training — as clear machine-readable preferences.
- **maintainer:** Cloudflare (Content Signals Policy; published openly under CC0)
- **governance_body:** vendor (Cloudflare); spec released under CC0
- **license:** CC0 (the policy text is released under a CC0 license for open adoption)
- **maturity_tag:** emerging
- **current_spec_version:** — (verify-against-primary-at-build)
- **spec_date:** 2025-09-24
- **launch_date:** 2025-09-24
- **last_verified:** 2026-06-15
- **transport:** robots.txt extension (Content-Signal directive: search / ai-input / ai-train)
- **core_mechanism:** The policy adds a short human-readable block plus a machine-readable Content-Signal line to robots.txt declaring per-use preferences with yes/no values: search (use in a search index), ai-input (use to ground/answer queries, e.g. RAG), and ai-train (use to train models). Cloudflare's managed robots.txt defaults to search=yes, ai-train=no. Signals express preferences, not technical enforcement.
- **discovery_endpoint:** robots.txt Content-Signal directive
- **settlement_type:** —
- **adoption_metric:** Auto-applied to Cloudflare's managed robots.txt (Cloudflare states 3.8M+ domains) with default Content-Signal: search=yes, ai-train=no (source: https://blog.cloudflare.com/content-signals-policy/)
- **notable_adopters:** {"value":"Cloudflare (creator; applied across its managed robots.txt fleet)","source":"https://blog.cloudflare.com/content-signals-policy/"}
- **relationships:** {"predicate":"complements","target":"rsl","note":"Content Signals expresses non-binding use preferences in robots.txt; RSL declares enforceable machine-readable licensing terms — paired Layer-6 declarations."}, {"predicate":"extends","target":"agents-json","note":"Content Signals is a robots.txt extension in the same Layer-1/6 declaration family as the other root-file declarations; it adds an after-access use dimension robots.txt's allow/disallow lacks."}
- **ideal_use_case:** A site that wants to state, in robots.txt, that search use is welcome but AI training is not — without standing up enforcement.
- **when_to_use:** When you want to communicate after-access content-use preferences (search vs AI-input vs AI-train) to crawlers in a standard, machine-readable line.
- **when_not_to_use:** When you need binding, enforceable licensing or payment (use RSL or Pay Per Crawl) — Content Signals are preferences, not controls.
- **code_example:** # robots.txt
# Content usage preferences (Cloudflare Content Signals Policy)
User-agent: *
Content-Signal: search=yes, ai-input=yes, ai-train=no
Allow: /
- **source:** Launch 2025-09-24, three signals (search / ai-input / ai-train), robots.txt extension, CC0, Cloudflare managed-robots default search=yes/ai-train=no, contentsignals.org: https://blog.cloudflare.com/content-signals-policy/ . Listed for addition in research §2.
- **agent_readiness_link:** access-economics
- **layer_legacy:** content