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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description's 'Read-only.' is redundant. However, it adds valuable behavioral context beyond annotations: pagination ('pages through'), the restriction to 'posted lines' (excluding unposted entries), and the balance structure (opening, running, closing). This enriches the agent's understanding of what happens when invoking the tool.

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 a single, front-loaded sentence with an em-dash clarification, plus a redundant but short 'Read-only.' note. Every word earns its place; it is concise and well-structured.

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 output schema exists and annotations cover the safety profile, the description provides sufficient core context: pagination, single-account scope, posted lines, and balance types. It does not elaborate on parameter usage, but the required parameters are obvious from the schema and the description's focus on 'one account'. This is slightly above adequate.

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 only 25% (just 'UUID value wrapper' for companyId and glAccountId), and the description does not compensate. It mentions 'one account' which hints at glAccountId and 'pages through' which relates to pagination parameters, but it does not explain optional parameters like basis, startDate, endDate, or currencyCode. The description adds minimal meaning beyond the schema param names.

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 uses a specific verb 'pages through' and clearly identifies the resource: one account's posted lines with opening, running, and closing balances. It distinguishes from siblings by emphasizing 'one account' and 'account register', which differentiates it from broader financial reports like balance sheet or trial balance.

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 phrase 'one account's posted lines' gives clear context that this tool is for single-account detail, implying it is not for multi-account or financial statement views. However, it does not explicitly name alternatives or exclusions, so it stops short of a full 5.

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