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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real context beyond that: breadth of coverage (21,000+ stocks, 60+ countries), daily refresh, and a full inventory of what the returned card contains, including that stored AI analysis only appears when one 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?

Front-loaded with the trigger condition and alternatives before the long card inventory. The enumeration of card contents is dense but earns its place since there is no output schema, though it could be tightened slightly.

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 return values and does so thoroughly, plus coverage, freshness and routing. Nothing an agent needs to select or call this tool 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 coverage is 100% and the single 'stock' parameter already documents accepted forms (ticker, company name, exchange-suffixed symbols), so the schema does the heavy lifting. The description only implies the input type by saying 'one company or ticker' and adds no format or edge-case guidance beyond that, matching the baseline for a fully documented single param.

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+resource ('explain a stock in plain English') and enumerates exactly what the response card contains, so an agent knows the shape of the answer. It explicitly distinguishes itself from check_value, which is the most confusable sibling.

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?

Gives concrete trigger utterances ('tell me about X', 'how is X doing', 'explain X stock') and then names the exclusion case with the alternative: for 'is X a good buy' or 'is X undervalued', use check_value instead. This is explicit when-to-use plus when-not-to-use plus the replacement.

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