AgentFuse has clear, well-structured tool definitions with complete input schemas and descriptions. All 4 tools follow verb_noun naming (create_budget_session, track_tokens, check_budget, get_session_report). Descriptions are substantive (100-200 chars) and explain WHAT the tool does and WHEN to use it. Parameters have types and descriptions. However, output schemas are not formally documented, responses are inferred from code inspection. Error handling is present but lacks recovery guidance (e.g., 'Session not found' doesn't suggest next steps). No tool annotations (readOnlyHint, destructiveHint, idempotentHint). The domain is narrow and well-executed, but lacks production-grade polish.

• Add formal output schemas to each tool definition. Document return types, required fields, and structure. Example: track_tokens returns {ok: boolean, halt: boolean, session_id: string, total_cost_usd: number, remaining_usd: number, ...}.
• Enhance error messages with actionable recovery steps. Replace 'Session not found' with 'Session not found. Create one first: call create_budget_session(session_id="...", budget_usd=10.0, model="gpt-4o")'.
• Add tool annotations: mark check_budget and get_session_report with readOnlyHint=true; mark create_budget_session and track_tokens with destructiveHint=true to signal state mutation.
• Document parameter constraints in descriptions. For budget_usd, add '(positive number, USD)'. For model, add '(e.g., gpt-4o, claude-sonnet-4, gemini-2.5-flash, see pricing table)'.
• Clarify idempotency: document that track_tokens with identical session_id + input_tokens + output_tokens will add a duplicate call record (non-idempotent). Suggest using call_label to deduplicate or implement server-side deduplication.