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

Annotations already cover the read-only/idempotent safety profile, and the description adds substantial extra behavior: oldest-first ordering, paging, a 50,000-fill ceiling, decimal-vs-1e-6 unit conversion, per-fill market naming, a 5-minute download link, and 404 meaning. This is rich disclosure beyond the 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?

Front-loaded with purpose and packed with only substantive detail across two sentences. Slightly dense clause-chaining (semicolons) but nothing is filler.

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: it describes the fill records, amount units, market naming, and the downloadable CSV link with its expiry. An agent has everything needed to call and interpret it.

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 baseline is 3, but the description adds real context for limit/offset by stating paging is 'a page at a time, up to its first 50,000 fills', which bounds what offset can reach beyond the schema's max 500 note.

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 names a specific verb and resource: reading one purchased daily file of a wallet's fills for one UTC day. It scopes the operation ('one purchased daily file') in a way that clearly separates it from sibling list tools like export_files, fills, and exports.

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 word 'purchased' implies a prerequisite (buy_export/subscribe) and the 404 note gives useful failure semantics, but no alternative tool is named and no explicit when-not-to-use guidance is given. Usage is implied rather than spelled out.

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