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

Annotations already establish read-only, idempotent, closed-world behavior. The description adds substantive return behavior: balance source (latest statement, stated value, or loan), as-of timing, gaps/jumps between statements, and account_id expanding to ordered statements and stated values.

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 dense sentences front-load the list behavior and then the account_id variation, with no filler. Phrasing like 'as of when' is slightly cryptic but compact.

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 only two optional parameters, no output schema, and annotations covering safety, the description supplies enough return-shape detail for an agent to call it correctly. It could clarify list ordering and what 'gap or jump' means, but those are minor.

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% and documents both optional parameters. The description adds meaning beyond the schema for account_id by explaining the single-account expansion and mentions balance 'as of' the as_of date, though it does not add date syntax.

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?

States that it returns every account with its balance, how the balance is derived, as-of timing, and statement gaps; the conditional sentence clarifies the single-account mode. It is clear but does not differentiate from sibling tools such as rec_accounts or purch_net_worth.

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?

Provides branch guidance: omit account_id to list accounts, supply it to get one account with its statements and stated values. It does not state when to use this versus related sibling tools or any exclusions.

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