.NET: Python: .NET: Make skill resource guidance rule-only

dotnet/src/Microsoft.Agents.AI/Skills/AgentSkillsProvider.cs

@@ -158,8 +158,9 @@ You have access to skills containing domain-specific knowledge and capabilities.
         When a task aligns with a skill's domain, follow these steps in exact order:
         - Use `load_skill` to retrieve the skill's instructions.
         - Follow the provided guidance.
-        - Use `read_skill_resource` to read any referenced resources, using the name exactly as listed
-           (e.g. `"style-guide"` not `"style-guide.md"`, `"references/FAQ.md"` not `"FAQ.md"`).
+        - Use `read_skill_resource` only for a resource explicitly referenced by the loaded skill.
+        - Pass its resource path exactly as written in that skill.
+        - Never infer or guess resource paths.
         - Use `run_skill_script` to run referenced scripts, using the name exactly as listed.
         Only load what is needed, when it is needed.
         """;

dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/AgentSkillsProviderTests.cs

@@ -79,6 +79,26 @@ public async Task InvokingCoreAsync_WithSkills_AppendsInstructionsAndToolsAsync(
         Assert.Contains("run_skill_script", toolNames);
     }
 
+    [Fact]
+    public async Task InvokingCoreAsync_DefaultPromptUsesRuleOnlyResourceGuidanceAsync()
+    {
+        // Arrange
+        var skill = new AgentInlineSkill("resource-guidance", "Resource guidance test", "Body.");
+        var provider = new AgentSkillsProvider(skill);
+        var invokingContext = new AIContextProvider.InvokingContext(this._agent, session: null, new AIContext());
+
+        // Act
+        var result = await provider.InvokingAsync(invokingContext, CancellationToken.None);
+
+        // Assert
+        Assert.NotNull(result.Instructions);
+        Assert.Contains("only for a resource explicitly referenced by the loaded skill", result.Instructions);
+        Assert.Contains("Pass its resource path exactly as written in that skill", result.Instructions);
+        Assert.Contains("Never infer or guess resource paths", result.Instructions);
+        Assert.DoesNotContain("style-guide", result.Instructions);
+        Assert.DoesNotContain("references/FAQ.md", result.Instructions);
+    }
+
     [Fact]
     public async Task InvokingCoreAsync_NullInputInstructions_SetsInstructionsAsync()
     {
@@ -439,6 +459,25 @@ public async Task LoadSkill_DefaultOptions_ReturnsFullContentAsync()
         Assert.Contains("Skill body.", text);
     }
 
+    [Fact]
+    public async Task LoadSkill_ListsExplicitResourcePathExactlyAsync()
+    {
+        // Arrange
+        var skill = new AgentInlineSkill("resource-skill", "Resource path test", "Consult the explicitly referenced guide.");
+        skill.AddResource("references/actual-guide.md", "Guide content");
+        var provider = new AgentSkillsProvider(skill);
+        var invokingContext = new AIContextProvider.InvokingContext(this._agent, session: null, new AIContext());
+        var result = await provider.InvokingAsync(invokingContext, CancellationToken.None);
+        var loadSkillTool = result.Tools!.First(t => t.Name == "load_skill") as AIFunction;
+
+        // Act
+        var content = await loadSkillTool!.InvokeAsync(
+            new AIFunctionArguments(new Dictionary<string, object?> { ["skillName"] = "resource-skill" }));
+
+        // Assert
+        Assert.Contains("<resource name=\"references/actual-guide.md\"/>", content!.ToString());
+    }
+
     [Fact]
     public async Task LoadSkill_EmptySkillName_ReturnsErrorAsync()
     {

python/packages/core/agent_framework/_skills.py

@@ -1809,8 +1809,9 @@ def _indent_width(s: str) -> int:
 Only load what is needed, when it is needed."""
 
 RESOURCE_INSTRUCTIONS: Final[str] = (
-    "- Use `read_skill_resource` to read any referenced resources, using the name exactly as listed\n"
-    '   (e.g. `"style-guide"` not `"style-guide.md"`, `"references/FAQ.md"` not `"FAQ.md"`).\n'
+    "- Use `read_skill_resource` only for a resource explicitly referenced by the loaded skill.\n"
+    "- Pass its resource path exactly as written in that skill.\n"
+    "- Never infer or guess resource paths.\n"
 )
 
 SCRIPT_RUNNER_INSTRUCTIONS: Final[str] = (

python/packages/core/tests/core/test_skills.py

@@ -676,6 +676,20 @@ def test_default_prompt_contains_skills(self) -> None:
         assert "<description>Does stuff.</description>" in prompt
         assert "load_skill" in prompt
 
+    def test_default_prompt_uses_rule_only_resource_guidance(self) -> None:
+        skills = [
+            InlineSkill(frontmatter=SkillFrontmatter(name="my-skill", description="Does stuff."), instructions="Body"),
+        ]
+
+        prompt = SkillsProvider._create_instructions(None, skills)
+
+        assert prompt is not None
+        assert "only for a resource explicitly referenced by the loaded skill" in prompt
+        assert "Pass its resource path exactly as written in that skill" in prompt
+        assert "Never infer or guess resource paths" in prompt
+        assert "style-guide" not in prompt
+        assert "references/FAQ.md" not in prompt
+
     def test_skills_sorted_alphabetically(self) -> None:
         skills = [
             InlineSkill(frontmatter=SkillFrontmatter(name="zebra", description="Z skill."), instructions="Body"),
@@ -806,6 +820,18 @@ async def test_load_skill_preserves_file_skill_content(self, tmp_path: Path) ->
         result = await provider._load_skill(_raw_skills(provider), "my-skill")
         assert "See [doc](references/FAQ.md)." in result
 
+    async def test_load_skill_lists_explicit_resource_path_exactly(self) -> None:
+        skill = InlineSkill(
+            frontmatter=SkillFrontmatter(name="my-skill", description="Skill."),
+            instructions="Consult the explicitly referenced guide.",
+            resources=[InlineSkillResource(name="references/actual-guide.md", content="Guide content")],
+        )
+        provider = SkillsProvider([skill])
+
+        result = await provider._load_skill([skill], "my-skill")
+
+        assert '<resource name="references/actual-guide.md"/>' in result
+
     async def test_load_skill_unknown_returns_error(self, tmp_path: Path) -> None:
         provider = SkillsProvider.from_paths(str(tmp_path))
         await _init_provider(provider)