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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds real behavioral context beyond them: the 20-symbol cap, the account-must-be-online requirement, and the closed-market fallback that returns last price with marketOpen false. It stops short of noting rate limits or partial-failure behavior across a mixed symbol list.

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?

A single dense sentence front-loads the core capability, then appends operational caveats and a concrete call example. Nothing is padded, though the semicolon-chained clauses pack several independent facts into one sentence, which slightly hurts scannability.

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 need not be enumerated, yet the description still surfaces the one field that changes agent behavior (marketOpen false on a closed market). Combined with the online precondition and symbol cap, an agent has everything needed to call this 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% and each of the four parameters is documented in-schema, so the baseline is 3. The description echoes instruments being resolved to the account's own symbol wording but adds no syntax, defaults, or clarification of how `symbols` and `instruments` differ — the one genuinely ambiguous pair an agent must choose between.

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+resource (live bid/ask quotes) plus scope (up to 20 symbols/instruments, this account's broker). That is enough to tell an agent what it retrieves. It does not differentiate itself from the nearby sibling get_symbol_snapshot, which plausibly competes for the same intent.

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?

Useful preconditions are given — the account must be online, and closed markets return last price with marketOpen false. However there is no explicit when-to-use or when-not-to-use guidance versus get_symbol_snapshot or list_account_instruments, so routing between siblings is left to inference.

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