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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds meaningful behavioral detail by specifying the exact output fields and noting that the monthly history is chart-ready as a list of {month, return} objects, which goes beyond what annotations provide.

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 concise and structured: it first summarizes the returned metrics, then clarifies the shape of the monthly history field, and finally documents the parameter. Every sentence contributes useful information with no filler or repetition.

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 tool with a single parameter and no output schema, the description covers the main return values and the parameter source. Minor gaps remain, such as units for returns and possible error behavior for invalid IDs, but the overall context is sufficient for an agent to select and invoke the tool correctly.

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?

The schema only defines portfolio_id as an integer with no supporting description (0% coverage). The description compensates well by explaining that the ID must be one returned by list_my_portfolios, giving the agent a concrete source for valid values.

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 that the tool returns a portfolio overview with specific metrics (returns for multiple periods, Sharpe ratio, and a monthly-return time series). However, it does not explicitly differentiate itself from the similar sibling tool get_portfolio_performance, so it misses the highest bar for sibling distinction.

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 gives a useful prerequisite by saying portfolio_id must be one of the IDs returned by list_my_portfolios, but it does not explain when to choose this tool over alternatives like get_portfolio_performance or get_portfolio_analysis. Usage context is implied rather than explicit.

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