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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds a genuinely useful non-schema behavior: the required subscription tier. However, it does not explain verdict semantics, data freshness, or rate/refresh behavior, so it adds only modest value beyond 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?

Tightly written: one sentence enumerating the returned fields, one sentence for the access prerequisite. Front-loaded with the core deliverable and no filler, though it is a single dense clause that compresses several outputs.

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 no output schema, the description carries the return-value burden and does it well, enumerating verdict states and the specific metrics returned. The main gap is the absence of explicit differentiation from get_etf_flows, but for a 1-param read-only tool it is largely complete.

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?

One optional enum parameter (BTC/ETH) with 0% schema description coverage, but the enum values are self-explanatory and the description ('BTC and ETH spot ETF verdict') confirms the allowed values. It adds no syntax, default, or behavioral detail about the parameter, so it sits at the schema-lifting baseline.

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 resource and output: an ETF verdict (BUYING/SELLING/MIXED) plus day/7d/30d flows, consecutive-day run, BlackRock holdings and daily history. It is clearly the analytical 'verdict' layer rather than raw flows, though it never explicitly contrasts itself with the sibling get_etf_flows, so the agent must infer the distinction.

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 only guidance is an access prerequisite ('Needs the Flows Terminal pass, Builder, Scale or PRO'), which is useful context but not when-to-use guidance. It never says when to prefer this over get_etf_flows or get_global_flows, leaving the choice to inference.

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