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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering safety. The description adds valuable behavioral context such as the `pre_post_market` block and market-state flags, explaining that extended-hours data may be freshest when the regular session is closed. This goes beyond annotations but does not mention error behaviors or rate limits.

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?

The description is well-structured: a one-line purpose, a concise list of return fields, a clear alternative note, and an Args section. Every sentence serves a purpose, and the formatting makes it easy to scan.

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?

While there is no output schema, the description thoroughly enumerates the returned fields and explains the extended-hours context. It covers the key nuances of the tool (market-state flags, pre/post market) and provides sibling differentiation. Minor omissions like error handling are not critical for this read-only tool.

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?

The input schema has 0% description coverage for the sole parameter 'tickers', so the description must compensate. It explains that tickers are comma-separated and gives examples ('AAPL' or 'AAPL,MSFT,NVDA'), but it does not mention that the schema also accepts an array, and it omits details like case sensitivity or invalid ticker handling. Thus it adds some meaning but is not fully comprehensive.

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 description states a specific verb and resource: 'Real-time price quote for one or more stocks or ETFs.' It clearly distinguishes from siblings by explicitly noting 'For forex pairs use get_forex_quote; this endpoint is stocks/ETFs only.' This makes the purpose unmistakable.

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 description provides explicit usage guidance by naming an alternative tool for forex pairs ('For forex pairs use get_forex_quote') and states the scope limitation ('stocks/ETFs only'). This helps an agent choose this tool over related quote tools for other asset classes.

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