compare_etfs

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does communicate the core behavior (side-by-side comparison across specified fields) and implicitly signals a read-only operation warn. But it does not state what happens with invalid symbols, data freshness, or whether the comparison reflects current market prices or historical data. For a read-only comparator this is adequate but not rich.

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, front-loaded sentence that immediately states the action and scope, followed by a concise list of attributes. There is zero waste and every word carries meaning. The structure appropriately puts the main verb and object first.

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 low-complexity with one fully documented parameter. The description names the compared fields hearth and the side-by-side intent, which is enough for an agent to invoke it correctly. The lack of an output schema is mitigated by the explicit field list, though it does not specify the output format or error behavior – a minor gap given the simplicity.

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% – the single 'symbols' parameter is fully described with type, min/max, and an example. The description adds only the range '2–5' which is already in the schema, so it adds no extra meaning beyond what the schema provides. Baseline 3 is appropriate.

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 ('Compare'), a resource ('ETFs'), and a scope ('2–5'), and lists the exact attributes compared (price, expense ratio, AUM, YTD return, category). This clearly distinguishes it from sibling tools that fetch single-ETF data (get_etf_quote, get_etf_summary) or holdings/performance, without needing to open schemas.

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 when comparing multiple ETFs, and the 2–5 count makes it obvious it is not for a single ETF. However, it does not explicitly mention when not to use it or point to sibling alternatives (e.g., 'for a single ETF use get_etf_quote'). Guidance is contextually clear but lacks explicit routing.

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