get_vol_surface

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

The description adds substantial behavioral context beyond the readOnly/idempotent/non-destructive annotations: missing strikes appear under 'missing' with reasons, daysToExpiry counts to settlement date (not just trading date), and instrument-root ambiguity is resolved via 'underlying' and 'warnings'. These are valuable behavioral traits not inferable from annotations alone, and there is no contradiction.

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 long but every section earns its place, with bolded headings breaking up distinct concepts (deterministic repricing, don't collapse, settlement dates, missing strikes, instrument ambiguity). It is front-loaded with the core definition and then layers critical warnings. No filler or redundant phrasing.

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?

For a tool with 9 parameters and an output schema, the description covers the essential contextual pitfalls: settlement vs trading date, missing strike handling, root-symbol collisions, and usage cautions about term structure. The output schema exists, so return values need no elaboration. The tool is complex and the description fully equips the agent with the needed context.

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?

Schema description coverage is 78%, so the schema already explains most parameters. The description adds meaningful context for several: it explains sec_type disambiguation with the 'ES' example, trading_class resolution for same-day expiries, strike snapping behavior, and the rate-limit implication of max_strikes_per_expiry. This goes beyond the schema's dry definitions, though not exhaustively for all parameters.

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 returns IB's implied volatility surface for an underlying, with a grid of (expiry, strike) and specific fields. It uses a specific verb ('get') and resource ('volatility surface'), and the detailed behavior distinguishes it from sibling tools dealing with margin, greeks, stress, and orders.

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?

Extensive usage guidance is provided: it explains when to use the surface for local repricing, warns against collapsing the surface to a single number, advises reading the correct tenor and interpolating in total variance, and tells users to check the underlying instrument to avoid ambiguity. It gives clear context and practical 'how to use' directions, though it doesn't name alternative tools explicitly.

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