stock_extended_hours

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

Adds substantial behavioral details beyond annotations: explains session-specific behavior (null post_market during regular session), computed % changes, and data freshness. Annotations already declare readOnlyHint=true and destructiveHint=false, but description enriches with operational context.

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?

Well-structured with purpose first, then usage guidelines, behavior, and arguments/returns. Every sentence adds value without repetition. Efficiently communicates complex information in a compact form.

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?

Compensates fully for the lack of output schema by detailing the return structure (pre_market, regular, post_market objects with fields) and edge cases (nulls, weekends). Complete enough for an agent to understand and use the tool effectively.

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?

Despite 0% schema description coverage, the description provides clear examples (AAPL, NVDA, TSLA, SPY, ^GSPC) and clarifies that indices are supported. This adds significant meaning beyond the schema's basic type definition.

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 explicitly states it provides real-time pre-market and after-hours prices for US stock symbols, using specific verbs like 'returns' and specifying the resource. It distinguishes itself from sibling tools like stock_prices and yahoo_price by focusing on extended hours.

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?

Provides clear scenarios for when to use the tool (earnings reactions, overnight news, after-hours queries) and explains behavior during regular hours and weekends/holidays. However, it does not explicitly state when not to use it or direct users to alternatives like stock_prices for regular hours.

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