diff --git a/README.md b/README.md
index a3254c5..37105f2 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ docs agent-friendly. The spec focuses on meeting the technical constraints of
agent platforms (truncation limits, content negotiation, discovery); it does not
consider qualitative evaluation of content.
-**Status**: Draft (v0.5.0)
+**Status**: Draft (v0.5.1)
**Full spec**: [SPEC.md](SPEC.md) | **Website**: [agentdocsspec.com](https://agentdocsspec.com)
@@ -98,7 +98,7 @@ This spec is open for community review. We welcome:
- **Proposed changes**: Submit a pull request (open an issue first for
significant changes)
- **Platform data**: If you know a platform's truncation limits, contribute to
- [the Platforms tables](./site/content/platforms.md)
+ [the Platforms tables](https://agentdocsspec.com/platforms/)
- **Real-world results**: If you've evaluated your docs against this spec,
we'd love to hear what you found
diff --git a/SPEC.md b/SPEC.md
index 3c01912..611af1a 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -3,8 +3,8 @@
| | |
|--------------|--------------------------------------------------------------|
| **Status** | Draft |
-| **Version** | 0.5.0 |
-| **Date** | 2026-04-25 |
+| **Version** | 0.5.1 |
+| **Date** | 2026-05-08 |
| **Author** | Dachary Carey + community contributors |
| **URL** | https://agentdocsspec.com |
| **Repository** | https://github.com/agent-ecosystem/agent-docs-spec |
@@ -653,6 +653,10 @@ Because different agents hit different paths, this spec defines size checks for
**both** the markdown response (if available) and the HTML response. A site
that's only optimized for the markdown path is leaving most agents behind.
+For empirical observations of how specific platforms (Claude, Cursor, Copilot,
+Gemini, Windsurf Cascade, and others) handle retrieval, truncation, and
+summarization in practice, see [Agent platform comparisons](https://agentdocsspec.com/platforms/).
+
### `rendering-strategy`
- **What it checks**: Whether the HTTP response contains the page's actual
@@ -1503,7 +1507,7 @@ becomes available.
### Known Platform Limits
-Compare platform architecture and truncation limits in [Platforms](./site/content/platforms.md).
+Compare platform architecture and truncation limits in [Platforms](https://agentdocsspec.com/platforms/).
### What This Means for Threshold Selection
@@ -1598,6 +1602,17 @@ welcome.
## Changelog
+### v0.5.1 (2026-05-08)
+
+- Moved per-platform truncation data out of Appendix A into a new
+ [Platforms](https://agentdocsspec.com/platforms/) comparison page on the
+ site. Appendix A retains the spec's threshold rationale and points readers
+ to the platforms page for current per-platform observations. Category 3
+ (Page Size and Truncation Risk) now references the platforms page so
+ readers can connect threshold choices to empirical pipeline behavior. No
+ threshold or check definitions changed. Platforms page authored by
+ Rhyannon Rodriguez.
+
### v0.5.0 (2026-04-25)
- Split `llms-txt-directive` into two independent checks:
diff --git a/site/content/_index.md b/site/content/_index.md
index 9ffaaa9..171825d 100644
--- a/site/content/_index.md
+++ b/site/content/_index.md
@@ -1,5 +1,5 @@
---
-title: "Agent-Friendly Documentation Spec"
+title: "Can agents read your documentation?"
description: "A proposed specification for making documentation sites work well for coding agents."
---
@@ -30,6 +30,10 @@ severity.
**[Read the Full Spec](/spec/)**
+For empirical observations on how specific agent platforms (Claude, Cursor,
+Copilot, Gemini, and others) handle retrieval, truncation, and summarization,
+see **[Agent platform comparisons](/platforms/)**.
+
## Quick Start for Documentarians
If you can only do a few things, these have the highest impact:
diff --git a/site/content/platforms.md b/site/content/platforms/_index.md
similarity index 88%
rename from site/content/platforms.md
rename to site/content/platforms/_index.md
index 95484da..68e4474 100644
--- a/site/content/platforms.md
+++ b/site/content/platforms/_index.md
@@ -1,13 +1,22 @@
---
-title: "Platforms"
+title: "Agent platform comparisons"
description: "Agent platform comparisons for retrieval, truncation, and summarization layers."
+showTableOfContents: true
---
-| **Section** | **Description** |
-| ----------- | ------------------ |
-| [Retrieval](#retrieval) | How and when an agent fetches content |
-| [Truncation](#truncation) | What gets lost and whether agents report it |
-| [Summarization](#summarization) | What happens to content between retrieval and generation |
+| | |
+|------------------|----------------------------------------------------------------------------------|
+| **Author** | Rhyannon Rodriguez |
+| **Last updated** | 2026-05-08 |
+| **Methodology** | [Agent Ecosystem Testing](https://rhyannonjoy.github.io/agent-ecosystem-testing) |
+
+This page provides an overview of observed agent web fetch retrieval behavior across agent platforms. To clarify observed behavior, we break down the retrieval process into three key components that form most agent web fetch pipelines:
+
+- [Retrieval](#retrieval): How and when an agent fetches content
+- [Truncation](#truncation): What gets lost and whether agents report it
+- [Summarization](#summarization): What happens to content between retrieval and generation
+
+These observations inform the size thresholds and pipeline assumptions in the [Agent-Friendly Documentation Spec](/spec/), particularly [Category 3: Page Size and Truncation Risk](/spec/#category-3-page-size-and-truncation-risk).
## Retrieval
@@ -59,5 +68,5 @@ Observable outputs from default settings primarily inform the conclusions below.
| [Gemini API URL context](https://rhyannonjoy.github.io/agent-ecosystem-testing/docs/google-gemini-url-context-tool/methodology) | _API layer pipeline, undocumented_ | Pre-generation injection suggests processing occurs before LLM invocation. No transformation layer between retrieval and generation; LLM receives content directly and any summarization occurs as part of generation, not as an intermediate pipeline stage. |
| [GitHub Copilot](https://rhyannonjoy.github.io/agent-ecosystem-testing/docs/microsoft-github-copilot/methodology) | _Inferred via relevance-ranking, undocumented for web fetch_ | Reassembled excerpts, outputs that don't note discarded content, browser masquerading, and tool substitution patterns suggests an orchestrator-subagent relationship and not a linear, passive pipeline. Agent loop descriptions vary by implementation. [VS Code-Copilot docs](https://code.visualstudio.com/docs/copilot/agents/subagents) describe subagent delegation as _main agent-initiated_ for complex tasks with further config available, but [Copilot SDK docs](https://docs.github.com/en/copilot/how-tos/copilot-sdk/use-copilot-sdk/custom-agents) only describe subagents as configurable, and not default architecture. |
| MCP Fetch (reference server) | _None_ hard truncation at `max_length` | Passive, linear pipeline without a processing layer. |
-| [OpenAI web search](./open-ai-web-search-tool/methodology.md) | _Differs by API surface, undocumented_ | Chat Completions autonomously retrieves, but Responses' LLM actively manages search in the chain of thought with `open_page` and `find_in_page`, suggesting a processing layer, but not explicitly documented or named in either API responses. |
+| [OpenAI web search](https://rhyannonjoy.github.io/agent-ecosystem-testing/docs/open-ai-web-search-tool/methodology) | _Differs by API surface, undocumented_ | Chat Completions autonomously retrieves, but Responses' LLM actively manages search in the chain of thought with `open_page` and `find_in_page`, suggesting a processing layer, but not explicitly documented or named in either API responses. |
| [Windsurf Cascade](https://rhyannonjoy.github.io/agent-ecosystem-testing/docs/cognition-windsurf-cascade/methodology) | _Inferred via chunking, undocumented for web and docs search_ | Codebase research triggers [built-in subagent Fast Context](https://docs.windsurf.com/context-awareness/fast-context). Test prompts likely invoked Fast Context alongside web search. Chunk analysis, tool substitution, terminal execution, and workspace referencing suggest an extensive processing layer, not a passive, linear pipeline. |
diff --git a/site/layouts/_default/list.html b/site/layouts/_default/list.html
index cc58147..64c7650 100644
--- a/site/layouts/_default/list.html
+++ b/site/layouts/_default/list.html
@@ -44,11 +44,5 @@
-
- {{ i18n "list.no_articles" | emojify }}
-
-
{{ end }}
{{ end }}
diff --git a/site/static/llms.txt b/site/static/llms.txt
index 04afe91..c40d3e3 100644
--- a/site/static/llms.txt
+++ b/site/static/llms.txt
@@ -5,6 +5,7 @@
## Docs
- [Full Spec](https://agentdocsspec.com/spec/index.md): The complete specification with all checks, thresholds, and implementation guidance.
+- [Platforms](https://agentdocsspec.com/platforms/index.md): Comparison of agent platforms across retrieval, truncation, and summarization behavior.
- [Home](https://agentdocsspec.com/index.md): Overview, quick start guide, and background links.
## Tools