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

Annotations already establish read-only, idempotent, non-destructive behavior, so the description needn't restate safety. It adds real context beyond them by disclosing the return contents (legs, max profit and loss, breakevens, chance of profit, open links) and that results are computed off an example stock price. It does not explain how the days/iv inputs shift those example values.

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?

A single dense sentence that front-loads the strategy enumeration before the return-content clause; nothing is wasted. It is slightly overloaded in one parenthetical, but every element earns its place.

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?

With no output schema, the description correctly carries the burden of describing the return fields, and read-only annotations cover the safety profile. The remaining gap is how the three numeric inputs shape the reported examples and whether the list is static or price-dependent.

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 100%, so the days, spot and iv_pct parameters are already fully documented, which sets the baseline at 3. The phrase 'built on an example stock price' faintly ties the payload to the spot input but adds no syntax or meaning for days or iv_pct.

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 names a specific verb-plus-resource ('list the eleven standard structures the calculator knows') and enumerates exactly which structures are covered, so an agent knows precisely what comes back. It falls short of 5 because it never explicitly positions itself against siblings like credit_spread or debit_spread, though the enumeration implies the broader browsing role.

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?

Usage is only implied: the mention of 'a link to open each one' suggests this is a discovery step before invoking a specific spread tool, but there is no explicit when-to-use or when-not-to-use statement. Nothing tells the agent whether to prefer this over directly calling debit_spread.

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