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

Beyond the readOnly/openWorld annotations, the description discloses operationally critical behavior: the fixed 30-day window, publication one business day in arrears, the sign convention (positive = inflow), and the distinction between null (not yet reported) and 0 (no creations/redemptions). This is exactly the context an agent needs to interpret results correctly.

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 dense sentences, front-loaded with purpose and scope before the field-level detail. Every sentence earns its place: the null/0 semantics and reporting lag are non-obvious facts an agent would otherwise get wrong.

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-shape burden and does so: it enumerates ticker, issuer, net USD millions, and totalUsdM, and explains the null case. Nothing an agent needs to call or interpret this tool is missing.

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% and the enum of 16 assets is fully documented in the schema, so the description is not required to carry parameter meaning. It adds only 'one crypto asset' and fund-ticker examples, which is baseline-level value.

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 (get), resource (daily net flows of every spot ETF), and scope (one crypto asset, fund by fund, last 30 days). The phrase 'fund by fund' implicitly separates it from asset-level siblings like get_asset_flows and summary-level get_flows_summary, so an agent can distinguish it without opening a schema.

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 30-day window and single-asset scope imply when the tool applies, but the description never names an alternative or states an exclusion (e.g., 'for aggregate totals use get_flows_summary'). Usage must be inferred from the sibling list rather than from explicit routing guidance.

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