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

Beyond the readOnlyHint annotation, the description discloses three non-obvious behaviors: rows can carry different dates while a session settles and the Date column should be used, change is omitted when the immediately prior trading session is absent, and split-limited or partial 52-week ranges are marked. These edge cases materially affect interpretation and are invisible in the schema. The description is consistent with readOnlyHint=true, so no contradiction exists.

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?

Five sentences, each earning its place: the core return contract is front-loaded in sentence one, followed by the date-alignment caveat, the conditional omission rule, the quality-marker note, and the semantic scope disclaimer. There is no redundant or filler content.

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 present, the description serves as the response contract: it enumerates the returned fields (close, change, volume, trailing 52-week range) and covers the edge cases that affect interpretation. For a single-parameter, read-only data-fetch tool, nothing essential is missing for correct invocation or result interpretation.

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% — the tickers parameter is fully documented as an array of strings with a max of 25 and accepted class-share formats (BRK-B or BRK.B). The description adds no parameter-level detail beyond what the schema already provides, so the baseline of 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?

The first sentence names a specific verb and resource: 'Get each ticker's newest traded, settled daily close in USD, with one-session change, volume, and trailing 52-week closing range.' It enumerates the exact fields returned and closes with 'This is settled history, not an intraday quote,' which differentiates it from siblings like GetLiveQuote and GetStockPrices.

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 closing statement 'This is settled history, not an intraday quote' gives agents a clear boundary for when this tool is appropriate versus when it is not. However, it stops short of naming the explicit alternative (GetLiveQuote) for live intraday needs, so the routing is clear but not fully spelled out.

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