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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds useful context beyond annotations: it requires a 'built period,' returns account-by-account totals, and includes memos and exceptions. This meaningfully clarifies what the tool will and won't do.

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 compact and front-loaded with the core report contents, then adds a useful pointer to ledger_lines. The phrasing 'Pro; ledger_lines gives the lines free' is slightly awkward but does not waste words.

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?

Despite having no output schema, the description enumerates the main report fields and prerequisites. It could be more explicit about what 'built period' means and what happens if the period is not built, but the essentials for selecting and invoking the tool are present.

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 already documents from, to, and currency thoroughly. The description does not add parameter-specific semantics, but with full schema coverage, this is an acceptable baseline.

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 tool's job: report a built period account by account, listing debits, credits, movement, closing balance, purchase commitments, and exceptions. It also distinguishes itself from ledger_lines by noting that ledger_lines provides the line-level detail.

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 clear context for what the report covers and points to ledger_lines as the tool that 'gives the lines free,' signaling when to choose the sibling instead. It does not enumerate all sibling tools, but the main alternative is covered.

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