refactor(hephaestus): clarify tool call philosophy for direct tools vs agents

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src/agents/hephaestus/gpt-5-4.ts

@@ -134,9 +134,11 @@ ${exploreSection}
 ${librarianSection}
 
 <tool_call_philosophy>
-More tool calls = more accuracy. Ten tool calls that build a complete picture are better than three that leave gaps. Your internal reasoning about file contents, project structure, and code behavior is unreliable - always verify with tools instead of guessing.
+More direct tool calls = more accuracy. Ten greps and file reads that build a complete picture are better than three that leave gaps. Your internal reasoning about file contents, project structure, and code behavior is unreliable - always verify with direct tools (grep, rg, file reads, AST-grep, lsp) instead of guessing.
 
-Treat every tool call as an investment in correctness, not a cost to minimize. When you are unsure whether to make a tool call, make it. When you think you have enough context, make one more call to verify. The user would rather wait an extra few seconds for a correct answer than get a fast wrong one.
+Treat every direct tool call as an investment in correctness, not a cost to minimize. When you are unsure whether to read a file or search for a pattern, do it. When you think you have enough context, make one more read to verify. Direct tools are cheap and fast - use them liberally.
+
+Explore/librarian agents are heavier - they spawn full subagents. Use them when you need cross-cutting codebase understanding, unfamiliar module structure, or multi-angle investigation that a single grep cannot cover. Do not fire explore agents for simple lookups that direct tools can answer.
 </tool_call_philosophy>
 
 <tool_persistence>
@@ -154,13 +156,12 @@ Before taking an action, check whether prerequisite discovery or lookup is requi
 Prefer tools over guessing whenever you need specific data (files, configs, patterns). Always use tools over internal knowledge for file contents, project state, and verification.
 
 <parallel_execution>
-Parallelize aggressively - this is where you gain the most speed and accuracy. Every independent operation should run simultaneously, not sequentially:
+Parallelize aggressively - this is where you gain the most speed and accuracy. Every independent direct tool call should run simultaneously, not sequentially:
 - Multiple file reads: read 5 files at once, not one by one
 - Grep + file reads: search and read in the same turn
-- Multiple explore/librarian agents: fire 3-5 agents in parallel for different angles on the same question
-- Agent fires + direct tool calls: launch background agents AND do direct reads simultaneously
+- Direct tools + agent fires: launch background agents AND do direct reads simultaneously
 
-Fire 2-5 explore agents in parallel for any non-trivial codebase question. Explore and librarian agents always run in background (\`run_in_background=true\`). Never use \`run_in_background=false\` for explore/librarian. After launching, continue only with non-overlapping work. If nothing independent remains, end your response and wait for the completion notification.
+For explore/librarian agents specifically: use them when the question requires cross-module understanding or multiple search angles that direct tools alone cannot cover. When you do fire them, fire 2-3 in parallel with different search angles. Always run in background (\`run_in_background=true\`). Never use \`run_in_background=false\` for explore/librarian. After launching, continue only with non-overlapping work. If nothing independent remains, end your response and wait for the completion notification.
 </parallel_execution>
 
 How to call explore/librarian: