get_portfolio_performance

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

With no annotations, the description carries the full burden of behavioral disclosure. It states it returns a timeseries, which is useful, but does not mention read-only nature, pagination, date handling nuances, or any limitations. It is not misleading, but it only minimally addresses behavior beyond the tool's name.

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 two concise sentences. The first sentence states the core function, the second provides a use case. No filler content, front-loaded and efficient.

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?

The tool is moderately simple with 4 parameters and no output schema. The description gives a clear purpose and usage context, which is sufficient for an agent to decide when to call it. It could be more complete by describing the timeseries structure, but the overall context is adequate given the sibling tools.

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 75% (3 of 4 params have descriptions), so the baseline is 3. The description adds little parameter-specific detail beyond 'over a date range', which aligns with startDate/endDate but does not clarify interval or accountIds semantics. It does not offset the gap for interval.

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 the tool returns a TWROR timeseries for the portfolio over a date range. It distinguishes from siblings like get_portfolio_valuation or get_portfolio_yield by specifying 'performance' and the use case. The verb 'Get' is specific and the resource is well-defined.

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 explicitly says 'Use this to answer "how did my portfolio perform this year / last 5 years?"', which provides clear context for when to use it. It does not include when-not-to-use or alternative tool names, 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.