diff --git a/.agents/skills/rea-tool-design/SKILL.md b/.agents/skills/rea-tool-design/SKILL.md
new file mode 100644
index 000000000..f4ba7894e
--- /dev/null
+++ b/.agents/skills/rea-tool-design/SKILL.md
@@ -0,0 +1,20 @@
+---
+name: rea-tool-design
+description: Design or change REA investigation tools, CLI/MCP contracts, provider capabilities, and Evidence semantics.
+---
+
+# REA tool design
+
+Use the [tool-design guide](../../../docs/tool-design.md) for tool boundaries,
+contract semantics, provider ownership, and discoverability. Inspect the current
+contract and nearest existing tool relevant to the analyst question; source,
+documentation, and live catalogs may describe different versions.
+
+For a design request, return the proposed boundary, input/result shape, Evidence
+semantics, nearest alternative, and verification approach. Implement when
+requested, preserving the user's scope and existing authorization.
+
+For implementation or verification, consult [testing](../../../docs/testing.md)
+for the affected consumer and provider lanes, and
+[contributing](../../../CONTRIBUTING.md) for generated-file ownership. Read
+provider/workflow guides only as the task requires.