diff --git a/docs/development/STRUCTURE.md b/docs/development/STRUCTURE.md
index 57cb7e4e9b..cac2f2d875 100644
--- a/docs/development/STRUCTURE.md
+++ b/docs/development/STRUCTURE.md
@@ -269,7 +269,8 @@ shared/
 │   ├── client.py           # run_agent(), run_agent_async()
 │   ├── command.py          # build_agent_command() for orchestrator-spawned containers
 │   ├── result.py           # AgentResult dataclass
-│   └── tool_interceptor.py # Pre-execution file write checks (Write/Edit/NotebookEdit) against role restrictions
+│   ├── tool_interceptor.py # Pre-execution file write checks (Write/Edit/NotebookEdit) against role restrictions
+│   └── tool_output_cap.py  # Predictive PreToolUse cap for built-in CC tools (Read/Grep): denies calls likely to overflow the 1 MB SDK buffer before they run; tunable via EGG_TOOL_OUTPUT_CAP / EGG_READ_CAP_BYTES (#2876)
 ├── egg_anchor/             # Agent anchor mechanism for post-compaction state recovery
 │   ├── __init__.py         # Public API exports
 │   ├── models.py           # Pydantic models (AgentAnchor, AnchorMeta, ProgressItem, Decision, BRCState)
diff --git a/docs/reference/agent-tools.md b/docs/reference/agent-tools.md
index 782a8eb7d1..f2f1be4642 100644
--- a/docs/reference/agent-tools.md
+++ b/docs/reference/agent-tools.md
@@ -232,6 +232,15 @@ falls back to the 100 KB default. The orchestrator measures the cap
 against `indent=2`-serialized JSON (matching what its MCP server ships),
 so raising the cap toward the buffer size stays safe.
 
+**Built-in tool cap (complementary):** The cap above covers egg-owned MCP
+`@tool` payloads. Built-in Claude Code tools (`Read`, `Grep`, etc.) run
+inside the CLI and can't be wrapped the same way. [#2876](https://github.com/jwbron/egg/issues/2876)
+adds a PreToolUse hook that predicts overflows *before* the tool runs and
+denies the call with a narrowing hint. See
+[Agent Recovery → Predictive Output Cap](agent-recovery.md#predictive-output-cap-pretooluse)
+for the heuristic table and the `EGG_TOOL_OUTPUT_CAP` / `EGG_READ_CAP_BYTES`
+operator knobs.
+
 ### `cli_command=None` rationale pattern (decision-13)
 
 A `ToolRegistration` declares `cli_command=None` for verbs that have