From fbf2398fb80260ed418317136b2da81edb54dd97 Mon Sep 17 00:00:00 2001
From: gustav-fff <286169375+gustav-fff@users.noreply.github.com>
Date: Thu, 13 Aug 2026 08:07:00 -0700
Subject: [PATCH] fix(mcp): declare readOnlyHint on all tools (#771)

find_files, grep, and multi_grep only read the filesystem but declared
no MCP tool annotations, so plan-mode / read-only clients blocked them.
Add annotations(read_only_hint = true, destructive_hint = false,
open_world_hint = false) to each #[tool].

Closes #771
---
 crates/fff-mcp/src/server.rs | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/crates/fff-mcp/src/server.rs b/crates/fff-mcp/src/server.rs
index c4affa334..3bef95ff8 100644
--- a/crates/fff-mcp/src/server.rs
+++ b/crates/fff-mcp/src/server.rs
@@ -421,7 +421,12 @@ impl FffServer {
     /// IMPORTANT: Keep queries SHORT — prefer 1-2 terms max.
     #[tool(
         name = "find_files",
-        description = "Fuzzy file search by name. Searches FILE NAMES, not file contents. Use it when you need to find a file, not a definition. Use grep instead for searching code content (definitions, usage patterns). Supports fuzzy matching, path prefixes ('src/'), and glob constraints ('name **/src/*.{ts,tsx} !test/'). IMPORTANT: Keep queries SHORT — prefer 1-2 terms max. Multiple words are a waterfall (each narrows results), NOT OR. If unsure, start broad with 1 term and refine."
+        description = "Fuzzy file search by name. Searches FILE NAMES, not file contents. Use it when you need to find a file, not a definition. Use grep instead for searching code content (definitions, usage patterns). Supports fuzzy matching, path prefixes ('src/'), and glob constraints ('name **/src/*.{ts,tsx} !test/'). IMPORTANT: Keep queries SHORT — prefer 1-2 terms max. Multiple words are a waterfall (each narrows results), NOT OR. If unsure, start broad with 1 term and refine.",
+        annotations(
+            read_only_hint = true,
+            destructive_hint = false,
+            open_world_hint = false
+        )
     )]
     fn find_files(
         &self,
@@ -536,7 +541,12 @@ impl FffServer {
     /// Prefer plain text over regex. Filter files with constraints.
     #[tool(
         name = "grep",
-        description = "Search file contents. Search for bare identifiers (e.g. 'InProgressQuote', 'ActorAuth'), NOT code syntax or regex. Filter files with constraints (e.g. '*.rs query', 'src/ query'). Use filename, directory (ending with /) or glob expressions to prefilter. See server instructions for constraint syntax and core rules."
+        description = "Search file contents. Search for bare identifiers (e.g. 'InProgressQuote', 'ActorAuth'), NOT code syntax or regex. Filter files with constraints (e.g. '*.rs query', 'src/ query'). Use filename, directory (ending with /) or glob expressions to prefilter. See server instructions for constraint syntax and core rules.",
+        annotations(
+            read_only_hint = true,
+            destructive_hint = false,
+            open_world_hint = false
+        )
     )]
     fn grep(
         &self,
@@ -573,7 +583,12 @@ impl FffServer {
     /// Patterns are literal text — NEVER escape special characters.
     #[tool(
         name = "multi_grep",
-        description = "Search file contents for lines matching ANY of multiple patterns (OR logic). IMPORTANT: This returns files where ANY query matches, NOT all patterns. Patterns are literal text — NEVER escape special characters (no \\( \\) \\. etc). Faster than regex alternation for literal text. See server instructions for constraint syntax."
+        description = "Search file contents for lines matching ANY of multiple patterns (OR logic). IMPORTANT: This returns files where ANY query matches, NOT all patterns. Patterns are literal text — NEVER escape special characters (no \\( \\) \\. etc). Faster than regex alternation for literal text. See server instructions for constraint syntax.",
+        annotations(
+            read_only_hint = true,
+            destructive_hint = false,
+            open_world_hint = false
+        )
     )]
     fn multi_grep(
         &self,