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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is known. The description adds valuable behavioral context by specifying the data source (Yahoo Finance) and the comprehensive list of returned fields (price, 52-week range, volume, market cap, etc.), which helps the agent set expectations without contradicting annotations.

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 two sentences, front-loads the action, and every sentence earns its place. The first sentence states the purpose and source; the second lists return fields and use cases. No fluff or redundancy.

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?

For a single-parameter read-only tool with no output schema, the description fully covers what data is returned and what it's used for. The annotations cover safety, and the sibling list clarifies scope. Nothing critical 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 for the only parameter (ticker) is 100%, with a clear description and examples. The tool description adds no extra parameter-specific detail, but the schema already fully documents the parameter, so the baseline of 3 is 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?

The description uses a specific verb 'Retrieve' with a clear resource: 'stock market data for individual ticker symbols from Yahoo Finance.' It enumerates the exact data fields returned and implicitly distinguishes itself from siblings like get_crypto_prices and get_exchange_rates by focusing on individual stock tickers.

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 explicitly states 'Use for fundamental analysis, stock screening, or building financial dashboards,' which gives clear context for when this tool is appropriate. While it doesn't explicitly exclude alternatives, the focus on individual tickers and the sibling names make the boundaries evident.

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