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

No annotations are provided, so the description carries the full behavioral burden. It adds genuine context ('All monetary values are decimals in the user's base currency'), which is useful, but says nothing about permissions, read-only nature, or rate limits. Adequate but incomplete for an annotation-free tool.

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 well-formed sentence that is front-loaded with the scope ('portfolio-level aggregates for a single portfolio') and then the returned fields. No wasted words, though the trailing currency note could be more tightly integrated.

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 takes on the job of explaining return values, and it does so by enumerating the aggregate metrics returned. Combined with the base-currency/decimal note, an agent knows what to expect. It would be complete at 5 if it also clarified the date-snapshot vs latest-price behavior.

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 both parameters (portfolioId and date) are already fully documented in the schema, including the reference to get_portfolios. The description adds no parameter syntax or format detail beyond what the schema supplies, so the baseline of 3 applies.

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 resource ('portfolio-level aggregates for a single portfolio') and enumerates exactly what it returns: market value, cost basis, realized/unrealized gains, cash balances, and total value. This is far more than a tautology. It falls short of a 5 because it never distinguishes itself from close siblings like get_portfolio_holdings or get_portfolio_balances.

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 implies usage by listing the aggregate fields, but never states when to choose this over get_portfolio_holdings, get_portfolio_balances, or get_portfolios. There is no when-to-use, when-not, or alternative routing guidance.

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