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

Annotations already establish this as a safe, read-only, idempotent, deterministic operation, so the safety burden is covered. The description adds genuinely useful behavioral disclosures not in annotations: unknown-before-holding crises are named 'not tested' rather than estimated, and amounts trigger a money-denominated view in the base currency.

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?

Front-loaded with the resource and the exact crisis scope, then usage guidance, then the parameter-dependent output behavior. The prose is compact and every clause carries information, though the distinctive 'not tested' policy sits at the end when it might belong earlier for routing decisions.

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 read-only analysis tool with a fully described schema and output schema, the description covers purpose, sibling routing, the holdings/amounts duality, base-currency handling, and the handling of pre-existence crises. Nothing material an agent needs in order to call it correctly or interpret its output is missing.

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 coverage is 100%, so both base and holdings are fully documented structurally, and the schema describes the holdings syntax (ticker: weight/amount, 1–100, cash handling). The description adds a layering detail the schema omits: numbers are interpreted as amounts in the base currency specifically to show each fall in money rather than as weights.

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?

States a specific verb+resource: it returns what named crises (2008, 2020, 2022) did to one portfolio, including the fall, worst day, and recovery days. It explicitly distinguishes itself from the sibling return_history and explains the 'not tested' labeling, so an agent can select it without inspecting the schema.

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?

Directly gives the trigger phrase ('what did crashes do to this?') and names the alternative sibling (return_history) for the whole record. It also notes that amounts produce per-crisis money figures, so the agent knows which parameter shape changes the output.

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