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

Goes well beyond the annotations, which only cover safety hints: it discloses the data source (Yahoo Finance with Nasdaq fallback), latency caveats ('exchange delays can apply'), failure behavior ('unknown symbols are returned as free 404s'), and a concrete billing rate ($0.002). These are exactly the operational traits an agent needs to plan a call.

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?

Effectively two sentences: the first front-loads what is returned, the second packs source, delay, error and cost into one line. No filler and no repetition of the schema.

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 takes on the burden of describing return contents and does so (price, change, ranges, volume, exchange, timestamp); combined with cost, fallback source and 404 behavior, nothing an agent needs to invoke it correctly 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?

Schema description coverage is 100% for the single 'symbol' parameter, so the schema already documents ticker format with examples. The description adds no syntax or format detail beyond that, making the baseline 3 appropriate.

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 ('look up') and resource (stock, ETF or index quote) and enumerates the returned fields, which tells the agent this is a live snapshot. It does not, however, differentiate itself from the sibling get_price_history, so the boundary between the two must be inferred.

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 word 'quote' and the listed live fields imply a current-snapshot use case, but there is no explicit when-to-use guidance and no mention of the alternative get_price_history for historical data. Usage is only implied.

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