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

Annotations already convey read-only, idempotent, and non-destructive behavior. The description adds genuinely useful behavioral context: the output is a download link valid for one hour and the CSV has one row per leg. It also signals the Pro-only nature of the tool without contradicting 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?

Two sentences carry the essential information with no filler: format, granularity, link expiry, Pro status, and the alternative. The most important action and constraints are front-loaded, and the alternative guidance is compactly placed at the end.

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?

Given the fully documented parameters, comprehensive safety annotations, and helpful pointer to ledger_lines for field semantics, the description is complete enough for an agent to select and invoke the tool correctly. The only slight terseness is the term 'leg,' but it is a domain term and not needed for successful invocation.

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 the schema fully documents parameters, date formats, inclusivity, prefix filtering, and currency behavior. The description mostly adds output-format context, not parameter-level detail, so the baseline score of 3 is appropriate.

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 clearly states the verb ('Return'), the resource ('the period's ledger lines'), the format ('RFC 4180 CSV'), and a structural detail ('one row per leg'). It also distinguishes itself from ledger_lines by noting it only reformats the same fields as CSV columns, making the tool's scope unmistakable.

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 explicitly names the alternative tool (ledger_lines), notes that it returns the same fields free and unlimited, and positions this tool as merely a CSV layout. This gives an agent a clear condition for choosing between export and the sibling data-access tool.

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