Get ETF snapshot

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

Beyond the readOnlyHint/destructiveHint annotations it adds genuinely useful behavior: unrequested modules are omitted, requested-but-unavailable modules are named explicitly (partial-result semantics), and ratios are returned in percentage points. The trailing 'Read-only' merely restates annotations, but the rest is substantive disclosure.

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?

Four short sentences, front-loaded with the core action and scope, then the parameter contract and the output-unit note. Only the closing 'Read-only' is wasted space since annotations already assert it.

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?

With an output schema present and annotations covering the safety profile, the description supplies exactly what remains: module selection semantics, defaulted omission behavior, handling of unavailable modules, and unit conventions. An agent could call this correctly without further inference.

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 the enum and default are already documented, but the description still adds meaning not in the schema — notably that fund_data carries NAV/AUM and that include drives both fetching and return shape. It does not explain cost of requesting all modules or how module ordering affects output.

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?

States a specific verb and resource ('Fetch a modular snapshot') and narrows scope to 'one exact ETF listing', which separates it from list-style siblings like search_etfs and screen_etfs. It does not name the adjacent per-fund siblings (get_etf_fund, get_etf_holdings, get_etf_exposures), so differentiation is good but not fully explicit.

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?

Usage is implied by 'one exact ETF listing' and by the include array controlling breadth, suggesting a one-call multi-module lookup. However, there is no explicit when-to-use/when-not statement and no named alternative for the narrower sibling tools such as get_etf_holdings or get_etf_risk.

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