diff --git a/.claude/rules/csharp.md b/.claude/rules/csharp.md
index 6cd5b2e..a06e90a 100644
--- a/.claude/rules/csharp.md
+++ b/.claude/rules/csharp.md
@@ -14,3 +14,4 @@ paths: ["**/*.cs"]
 - Functional types (Result, Maybe, Any) use implicit operators for ergonomic construction — maintain this pattern in new types.
 - Record types are preferred over classes for immutable value objects.
 - `TreatWarningsAsErrors=true` is global — never suppress a warning without understanding why it fires.
+- XML documentation comments (`///`) on public APIs are expected. No inline code comments (`//`, `/* */`) that explain code.
diff --git a/.kimi/skills/csharp-conventions/SKILL.md b/.kimi/skills/csharp-conventions/SKILL.md
index d96b18c..c0ca3c9 100644
--- a/.kimi/skills/csharp-conventions/SKILL.md
+++ b/.kimi/skills/csharp-conventions/SKILL.md
@@ -15,3 +15,4 @@ description: C# coding conventions for CSharpEssentials. Use when writing, revie
 - Functional types (Result, Maybe, Any) use implicit operators for ergonomic construction; maintain this pattern in new types.
 - Record types are preferred over classes for immutable value objects.
 - `TreatWarningsAsErrors=true` is global; never suppress a warning without understanding why it fires.
+- XML documentation comments (`///`) on public APIs are expected. No inline code comments (`//`, `/* */`) that explain code.
diff --git a/AGENTS.md b/AGENTS.md
index a9f771b..fcb6a48 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -45,7 +45,7 @@ Releases are automated with [release-please](https://github.com/googleapis/relea
 - Don't add `// TODO` to committed code — either implement it or track it as an issue.
 - Don't add new packages to `Directory.Packages.props` without checking existing entries.
 - Don't break multi-targeting — test against all declared target frameworks.
-- Don't add docstrings or comments unless explicitly asked.
+- Don't add inline code comments (`//`, `/* */`) that explain code unless explicitly asked. XML documentation comments (`///`) on public APIs are expected.
 - Don't create placeholder/stub implementations.
 
 ## Boundaries
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 860a28c..e48a1ec 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -154,7 +154,7 @@ We use GitHub issues to track public bugs. Report a bug by [opening a new issue]
 
 - Use 4 spaces for indentation
 - Follow C# coding conventions
-- Write XML documentation for public APIs
+- Write XML documentation for public APIs; do not add inline code comments that explain code
 - Keep methods small and focused
 - Use meaningful names for variables and methods
 
@@ -168,7 +168,7 @@ We use GitHub issues to track public bugs. Report a bug by [opening a new issue]
 ## Documentation
 
 - Update relevant documentation
-- Include XML comments for public APIs
+- Include XML documentation comments (`///`) for public APIs
 - Update README.MD if needed (package table, badges)
 - Update the package `Readme.MD` and the matching `.well-known/agent-skills/<package>/SKILL.md` when a public API changes
 - Do not bump the version or edit `CHANGELOG.md` in a feature pull request; release-please generates both