diff --git a/docs/turn-loop/mcp.md b/docs/turn-loop/mcp.md
index 0ea3378f..06446a7c 100644
--- a/docs/turn-loop/mcp.md
+++ b/docs/turn-loop/mcp.md
@@ -206,7 +206,10 @@ status hint moved to the wake prompt + UI header.
 
 ## Tool whitelist (`mcp_config::ALLOWED_BUILTIN_TOOLS`)
 
-- Allowed built-ins: `Edit`, `Glob`, `Grep`, `Read`, `Write`.
+- Allowed built-ins: `Edit`, `Glob`, `Grep`, `Read`, `Skill`, `Write`.
+  `Skill` is what makes an installed plugin's `SKILL.md` invokable —
+  without it, a skill's `description` frontmatter never gets seen by
+  the model no matter how well it matches the task.
 - Tool-group-gated built-ins: `WebFetch`, `WebSearch` (added when the
   `web_tools` tool group is enabled — see P3RM1SS10NS tab).
 - Denied by omission (absent from the harness `--tools` /
diff --git a/hive-agent/src/mcp_config.rs b/hive-agent/src/mcp_config.rs
index 15476d87..2f4820c7 100644
--- a/hive-agent/src/mcp_config.rs
+++ b/hive-agent/src/mcp_config.rs
@@ -22,13 +22,17 @@ pub const DEFAULT_MCP_HTTP_PORT: u16 = 8790;
 /// in this list (or added by `extra_builtin_tools`) literally doesn't
 /// exist in the session. Web egress (`WebFetch`/`WebSearch`) are
 /// tool-group-gated (`web_tools`) — off by default. Nested agents
-/// (`Task`) are intentionally omitted. `Bash` is disallowed — shell
+/// (`Task`/`Agent`) are intentionally omitted. `Bash` is disallowed — shell
 /// execution goes through `mcp__bash__run` (background tasks
 /// with structured output via `hive-bash-mcp`) instead of a raw interactive shell. `TodoWrite`
 /// is omitted because the todo list lives in claude's in-process session
 /// state and silently evaporates on /compact or session reset — agents
-/// should plan in /state notes instead.
-pub const ALLOWED_BUILTIN_TOOLS: &[&str] = &["Edit", "Glob", "Grep", "Read", "Write"];
+/// should plan in /state notes instead. `Skill` is included so installed
+/// plugin skills (`base@hyperhive` and friends) are actually invokable —
+/// without it here, every `SKILL.md`'s `description` frontmatter is inert:
+/// the model never sees the tool that triggers a skill, no matter how well
+/// it matches the task at hand.
+pub const ALLOWED_BUILTIN_TOOLS: &[&str] = &["Edit", "Glob", "Grep", "Read", "Skill", "Write"];
 
 /// Env var written by the meta renderer with a comma-separated list of
 /// `hive_sh4re::ToolGroup` `snake_case` names (e.g. `"messaging,inbox,meta"`).