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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context: the source (Yahoo Finance via yfinance), no API key requirement, and specific interval limits (max 730 days for 1h, max 60 days for intraday). However, it does not describe error behavior, rate limits, or what happens on invalid tickers. Given the annotations cover safety, the description contributes some behavioral detail but not rich context, so a 3 is warranted.

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 efficient, starting with the core purpose and then listing usage conditions and key options. It is structured with a bullet-like 'Use this tool when' section and a clear list of interval/period options. There is minimal redundancy, and the most important information (what it does) is front-loaded. It earns a 4 for being concise and well-organized.

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?

Given the tool's complexity (many parameters, nested objects, output schema), the description covers the essential usage context: what it returns, when to use it, key interval/period limits, and source/authentication details. The output schema is present, so return format need not be described. The description does not mention error handling or rate limits, but these are not critical for an agent to invoke the tool correctly. It is complete enough for correct invocation, so a 4 is appropriate.

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 0%, meaning the description text does not describe most parameters. The description does mention interval and period options, which maps to two of the many parameters, but it does not cover symbol, start, end, auto_adjust, actions, or the many filtering params. The schema itself provides descriptions for each parameter, so the agent still has structured guidance, but with low coverage the description should compensate more. It provides some value for interval/period but leaves others to the schema, so a 3 is fair.

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 ('Fetch') and resource ('OHLCV price history for one ticker'), which is clear and unambiguous. It does not explicitly name or differentiate from sibling tools like GetMultiTickerHistory, but the phrase 'for one ticker' implies the single-ticker scope, distinguishing it from multi-ticker alternatives. It is specific enough for an agent to understand the core function.

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 includes a 'Use this tool when' section with three concrete conditions (historical price/volume data, performance analysis, returns/volatility/trend analysis). This provides clear context on when to invoke the tool, though it does not explicitly state when not to use it or name alternatives. It gives actionable guidance without exclusions, so a 4 is appropriate.

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