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

Annotations already cover readOnly, idempotent, non-destructive and closed-world, so the safety profile is not the description's burden. The description usefully adds that bank accounts yield no holdings and that omitting the filter spans all investment/crypto accounts, which is behavioral context beyond 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, front-loaded with the action and returned fields, then the scoping exceptions. No filler.

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?

An output schema exists so return values needn't be explained, yet the description still names the key fields. With annotations covering safety and the sole parameter fully documented, nothing needed to call this tool correctly is missing.

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% for the single account_id parameter, and the description only restates the schema's own meaning ('Optionally restrict to one account'). Baseline 3 applies since the schema carries the parameter semantics.

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?

Specific verb (list) plus resource (investment and crypto positions) and enumerates the returned fields (symbol, asset class, quantity, price, market value, currency). It also draws the boundary that bank accounts have no holdings, which separates it from sibling balance/transaction tools.

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?

Gives clear context: it covers investment/crypto accounts, bank accounts are excluded, and the optional single-account narrowing is stated. It references list_accounts for the id but does not explicitly compare against get_account_balance or list_transactions, so an agent still has to infer the boundary rather than being routed.

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