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

Annotations already declare readOnly/idempotent/non-destructive, so the description rightly spends its words on semantics instead: survivorship-free construction, the $5 price floor and 63-day dollar-volume ranking behind index mode, the 500-row page size, and the today default. It does not state a total row count or whether offset paging terminates, which would have pushed this to 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?

Three dense sentences, front-loaded with the default behavior before the alternate index mode and paging. Every clause carries information, though the index-mode sentence is long and packs ranking method, price floor, and disclaimer together.

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 no output schema, the description adequately conveys what is returned (symbol lists, survivorship-free, point-in-time) and how to paginate. Only the absence of row-count/termination guidance keeps it from fully covering a listing tool whose results are paginated.

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%, so the baseline is 3; the description earns above that by explaining what 'index' actually returns (most-traded names priced at least $5, ranked by 63-day dollar volume) — meaning the enum label alone does not convey. It also documents the 500-row page size tied to 'offset', adding a concrete value the schema omits. 'prefix' is left entirely to the schema.

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 ('Returns every US symbol that was trading on as_of') with the critical qualifier 'including companies that later delisted (survivorship-free)'. It also explicitly separates the two modes (full universe vs. liquidity-ranked index subset), so an agent can distinguish it from data-fetching siblings like get_bars or get_fundamentals_pit.

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?

Clearly explains the two selectable modes and when each applies, plus the paging procedure ('Pages of 500; pass offset'). It flags the caveat that index mode is a point-in-time large-cap proxy rather than official index membership. It stops short of explicit when-not-to-use guidance or naming an alternative tool, but for a universe-listing tool the context is clear.

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