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

Annotations already cover readOnly, idempotent, non-destructive, and closed-world traits, so the bar is lower. The description usefully adds the auth/quota context (Pro API key needed for full history since launch) and the newest-first result ordering, which annotations do not convey.

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 tight sentences with no waste; the scope and ordering come first, followed by the one gating constraint. Nothing is redundant or buried.

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 so adequately (daily total net flows, newest first) while covering the key access constraint. Pagination behavior and the include_funds trade-off are left unaddressed, keeping it short of fully 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?

Schema description coverage is 100%, so asset, start_date, end_date, and include_funds are all documented in the schema itself. The description adds no parameter syntax or format detail beyond a general confirmation of what the dates bound, so the baseline 3 applies.

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?

Names a specific resource (daily total net flows in USD of US spot BTC or ETH ETFs) with the exact scoping constraint (between two dates, inclusive) and the ordering (newest first). This implicitly distinguishes it from siblings like get_latest_etf_flows and get_etf_flow_summary, which cover narrower or aggregated slices.

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 states a prerequisite ('History since launch requires a Pro API key') but gives no explicit when-to-use vs alternatives guidance against get_etf_flow_summary, get_fund_flows, or get_latest_etf_flows. Usage is only implied by the date-range framing.

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