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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral context beyond them: cost_basis and gain/loss can be null when the institution doesn't report it, pagination bounds (default 50, max 200), and a warnings array flagging banks that failed to contribute with an optional reconnect_url. It does not cover rate limits or auth requirements, but for a read-only list tool this is well above the annotation baseline.

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?

Three sentences, front-loaded with what is returned and how it is ordered, then operational details. Slight waste in restating pagination defaults that the schema already states verbatim, but overall tight and information-dense.

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?

There is no output schema, so the description carries the burden of describing return values — and it does, listing the position fields, the totals, and the warnings array shape with message and reconnect_url. Combined with pagination behavior, an agent has everything needed to call and interpret it correctly.

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 limit, offset and account_id fully; the description mostly restates the limit/offset defaults and max rather than adding new meaning. The account_id narrowing semantics (only results from one account) are already conveyed by the schema, so baseline 3 applies.

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 a specific verb and resource ("List current investment positions"), enumerates the returned fields, specifies ordering (largest value first) and that portfolio totals are included. This is clearly distinguishable from siblings like list_investment_transactions (transaction history) and list_accounts (account inventory).

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 this is the tool for current position data, but it never explicitly routes the agent away from list_investment_transactions or get_account, nor states prerequisites like needing a connected investment account. The only pointer to a sibling ("Use an account id returned by list_accounts") lives in the schema for account_id, not in the description.

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