run_scenario_analysis

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It discloses a key behavioral trait: the calculation is a 'linear delta/vega/theta approximation', and it also notes a prerequisite ('Get option Greeks from get_options_chain first') and an input format flexibility (plain text for stock-only portfolios). This adds valuable context beyond what the schema offers, though it doesn't cover error cases or side effects.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is efficiently organized with clear sections: purpose, usage triggers, args, and returns. Every sentence provides necessary information—no filler or redundancy. The JSON example is detailed yet not excessive.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's moderate complexity (4 params, one with complex JSON format) and absence of an output schema, the description covers the essentials: return structure ('Estimated P&L with per-Greek contributions'), approximation method, dependencies, and all parameter meanings. It lacks explicit edge-case or error-condition guidance, but for a what-if calculation tool, the provided context is largely sufficient.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 0% description coverage, so the description fully compensates. It includes a detailed example for 'positions' with a JSON array, notes the requirement to fetch Greeks first, and explains the plain-text alternative. It also gives meaningful one-line descriptions for stock_move_pct, iv_change_pct, and days_forward, specifying units and purpose.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: 'Run what-if scenario analysis on a portfolio' and explains it shows portfolio value changes under different market conditions with a specific approximation method. This distinguishes it from sibling tools like calculate_portfolio_greeks or calculate_expected_move by focusing on scenario simulation rather than current state or single-instrument moves.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit 'Use this tool when the user asks about' with three clear scenarios (what-if scenarios, portfolio P&L under conditions, price/vol sensitivity). It does not, however, name alternative tools or explicitly state when not to use it, so it stops short of full exclusion guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.