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

Annotations already declare readOnly, idempotent and non-destructive, so safety is covered. The description adds meaningful output behavior beyond that: prose sentences, no tables, no numbered report, and that supplying amounts makes the fall render in money at the base currency (default USD). This is genuine context the annotations do not carry.

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?

It is front-loaded with the output shape before the usage and currency details. The parentheticals make it slightly dense and it runs long for a two-parameter tool, but every sentence carries information.

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 an output schema, rich annotations, and 100% parameter coverage, the remaining burden is output style and routing, both addressed. A reader understands what they get and when to prefer it, so nothing critical 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 parameters are already documented. The description restates that amounts produce the fall in money and that base defaults to USD, which largely mirrors the schema rather than adding new syntax or constraints. Baseline 3 is appropriate.

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 states concretely what is produced: three or four plain-language sentences covering what a portfolio's risk is built from and its worst historical fall. It differentiates from siblings by pointing to measure_portfolio for figures and contrasting with 'no tables and no numbered report' (portfolio_report). It lacks a crisp action verb but the resource and output are unambiguous.

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?

It gives explicit selection context: 'Use it for the shortest answer, or for a reader new to investing', and routes the agent to measure_portfolio when figures are wanted. There is no explicit 'when not to use' beyond the report contrast, so it falls short of a 5.

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