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

Annotations declare readOnlyHint and idempotentHint, meaning the tool is safe and non-destructive. The description adds that every figure carries the date of the source file, which is valuable behavioral context for understanding data freshness. It also specifies the ordering of holdings (largest first), which helps set expectations.

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 sentences, front-loading the main purpose and then listing the data points. Every sentence adds value; no fluff or redundancy.

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?

Given the tool's moderate complexity, the schema covers parameters, annotations cover safety, and the description explains the output's scope. There is no output schema, but the description adequately details what the agent can expect, 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 parameters are documented. The description adds value by specifying that 'holdings' is the count of largest holdings to return, and that 0 means none, which is already in the schema but reinforced. It also clarifies that the output includes weights and other metrics, which is not in the parameter descriptions.

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 it returns a single US ETF's holdings with weights, cost, assets, returns, volatility, beta, worst fall, and concentration. The verb 'fund_profile' implies a profile, and the description specifies the resource ('US ETF') and the data included, distinguishing it from siblings that compare or list.

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 the tool is for inspecting a single ETF's detailed profile, as opposed to comparing or listing. It does not explicitly state when not to use it or name alternatives, but the context of 'one US ETF' and the sibling names provide clear guidance.

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