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

The description adds useful behavioral context beyond the annotations: it explains the minor-unit comparison and what happens when the trial balance does not tie. But annotations are all false/empty and the description does not clarify whether the tool is strictly read-only, whether it can mutate ledger data, or what the success path returns, leaving the side-effect profile to inference.

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 tightly written sentences lead with the core computation and follow with the important exceptional behavior. The phrase 'Free and unlimited' is the only minor extra, but it is short, relevant, and does not dilute the front-loaded meaning.

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?

The description clearly gives the period scope and the failure-mode output, which matters because there is no output schema. However, it does not describe the success return shape, the exact format of the named entries/source documents, or error behavior, so an agent must guess what the tool emits when the ledger actually balances.

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?

The input schema already documents all three parameters with 100% coverage, including the currency 'never added together' rule. The description's mention of 'period' and 'minor unit' loosely maps to from/to and currency but adds no new parameter-level syntax or constraints, so baseline 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 states a specific operation — total debits and credits for a period and prove they equal the minor unit — plus a distinctive failure behavior: naming unbalanced entries and their source documents. This clearly distinguishes trial_balance from generic report siblings like ledger_report or month_close.

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 implies use for period-end balance verification ('for a period') and describes the conditional diagnostic behavior when totals do not agree. However, it does not explicitly say when to prefer this over sibling tools such as ledger_report or month_close, nor does it state any when-not-to-use conditions.

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