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

Annotations already indicate read-only, idempotent behavior, and the description adds substantial context: the full return shape, per-row fields, the meaning of source_quality, and the disclaimer. It clarifies that source_quality is derived from each row's sources[], which goes beyond the structured 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?

The description is dense but well-structured, front-loading the core purpose and then enumerating output details and usage examples. It is somewhat long due to the rich return field breakdown, but every sentence contributes meaningful information.

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 fully compensates by enumerating the top-level and per-row fields, explaining tier and source_quality semantics, and giving usage examples. It provides enough context for an agent to invoke the tool and interpret results correctly.

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 covers both parameters with descriptions, so baseline is 3. The description adds value by clarifying filtering semantics ('country name or ISO code'), providing examples for each parameter, and explaining that empty input returns the full ranking — details not present in the schema alone.

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 begins with a specific verb and resource: 'Nation-state Bitcoin holdings, ranked largest first.' It clearly states what the tool returns and the ordering, and the 'Nation-state' qualifier distinguishes it from sibling tools like get_treasury_holdings.

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 gives explicit usage patterns: filter by country name or ISO code, filter by tier, and call with {} for the full ranking. It provides concrete examples but does not explicitly mention when not to use this tool or compare it to alternatives.

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