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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely non-obvious behavior: every value carries a source and timestamp, unread values are explicitly declared as such, and the stale-price rule is spelled out (stale only past the feed's heartbeat while a session is open). It doesn't explain failure behavior for an invalid ticker/contract, 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?

It is one very long run-on sentence packing ~10 data categories plus a disclaimer. Almost every clause carries real information given there is no output schema, so it isn't padding, but the lack of any structural break makes it hard to scan and it is not front-loaded beyond the opening identity clause.

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 carries the full burden of describing the return and does so field by field (listing, Chainlink price with age, pool price/venue/liquidity, spread, supply, oracle pause, corporate actions, SEC EDGAR data). What's missing is only the error/not-found path for an unrecognized ticker or contract.

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% and the single `id` parameter is fully documented including the '0x' + 40 hex contract form. The description repeats the ticker/contract duality with the same examples (NVDA, AAPL) rather than adding format details the schema lacks, 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?

Opens with a precise verb-less but specific identity statement: 'One Robinhood Stock Token ... by its ticker ... or its token contract', and even defines what the asset legally is (debt instrument, not a share). The singular 'One' implicitly separates it from the sibling stock_tokens, but that contrast is never made explicit, so it falls short of a 5.

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?

Usage is inferable — look up a single token by ticker or contract — but the description never states when to prefer this over stock_tokens for listing, nor any preconditions. No exclusions or alternatives are named despite the sibling's near-identical name.

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