List E*TRADE accounts

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavior beyond them: the tool is scoped to the current connection's readable accounts, and its output is the accountIdKey prerequisite for other E*TRADE tools, including the warning that a user-quoted account number will not work. It does not cover pagination or error behavior, which keeps it from a 5.

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 tight sentences, both carrying load. The purpose and the accountIdKey rationale come first, the call-ordering instruction second, with 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?

There is no output schema, so the description must convey what comes back; it does so by naming accountIdKey and warning about the account-number mismatch. For a zero-argument, read-only listing tool with annotations already covering safety, nothing essential 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?

Zero parameters, so the baseline is 4 and there is nothing for the schema to describe. The description usefully explains the semantic distinction between the returned key and the human-facing account number, which is the only parameter-adjacent ambiguity in this tool family.

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 (E*TRADE accounts) and an explicit scope qualifier ('this connection can read'). It also names the payload that matters (accountIdKey) and distinguishes itself from etrade_positions, so an agent can place it without reading any schema.

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 an explicit sequencing rule — call this before etrade_positions — which is exactly the guidance an agent needs for a prerequisite tool. It stops short of stating when not to call it or what to do if the list is empty, so it is clear but not exhaustive.

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