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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds value beyond annotations by disclosing that uncovered tickers are listed and skipped, and that results are ranked by overlap weight. No contradiction with annotations.

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?

Two tightly written sentences with no filler. The main function is front-loaded, and the edge-case behavior is added as a concise second sentence. Every word earns its place.

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 one-parameter, read-only tool with rich annotations, the description covers input bounds, output ordering, and edge-case behavior. It could specify the exact return structure, but the absence of an output schema is mitigated by the clear description of ranking and skipping.

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%, including ticker format, case-insensitivity, and the 2–30 bound. The description adds an important semantic nuance: uncovered tickers are not errors but are listed and skipped, which informs how invalid input is handled.

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 a specific verb and resource: computing pairwise ETF overlap and ranking by weight, with the clear use case of detecting duplicated portfolio holdings. It is informative and distinct from siblings like compare_funds, though it doesn't explicitly name or differentiate itself from any sibling.

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 clear context for use ('to see which funds in a portfolio duplicate each other') but provides no explicit when-to-use or when-not-to-use guidance, no exclusions, and no alternative tool names. Usage is implied rather than directly specified.

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