refactor(agents): simplify explore tool strategy guidance

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/agents/explore.ts

@@ -106,28 +106,12 @@ Your response has **FAILED** if:
 
 ## Tool Strategy
 
-**Default to \`grep\`** for almost every search. Use it for:
-- Text patterns: strings, comments, logs, config values, log tags
-- Case-insensitive or multi-line matching
-- Anything regex-shaped: alternation (\`foo|bar\`), wildcards (\`.*\`), escapes (\`\\w\`)
-
-Use \`ast_grep_search\` **only** when you need to match code by AST shape:
-- Callers of a function: \`callee($$$)\`
-- Declarations by shape: \`function $NAME($$$) { $$$ }\`, \`class $C { $$$ }\`, \`impl $T for $S { $$$ }\`
-- Structural rewrites that must survive whitespace or formatting changes
-
-Do **NOT use regex** inside \`ast_grep_search\`. None of these work:
-- \`foo|bar\` (alternation) - run multiple calls, or switch to grep
-- \`.*\`, \`.+\` (wildcards) - use \`$$$\` between AST fragments
-- \`\\w\`, \`\\d\` (escapes) - use \`$VAR\` for any identifier
-- \`[a-z]\` (character classes) - no AST equivalent
-
-If \`ast_grep_search\` returns zero matches, **read the hint** it prints. If the hint says your pattern is regex-shaped, do not retry with a different regex - **switch to grep**.
-
-Other tools:
-- **LSP** - semantic navigation: definitions, references, workspace symbols
-- **glob** - files by name or extension
-- **git** - history, blame, who-changed-what
+Use the right tool for the job:
+- **Semantic search** (definitions, references): LSP tools
+- **Structural patterns** (function shapes, class structures): ast_grep_search  
+- **Text patterns** (strings, comments, logs): grep
+- **File patterns** (find by name/extension): glob
+- **History/evolution** (when added, who changed): git commands
 
 Flood with parallel calls. Cross-validate findings across multiple tools.`,
   }