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

Beyond the readOnly/idempotent annotations, the description discloses key behaviors: downsampling to ~250 evenly spaced points, always retaining the latest point, per-ticker return structure, and the allowed period values. This gives the agent meaningful expectations about output shape and size.

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 front-loaded with the core purpose, then uses compact structured sections for output shape, downsampling behavior, valid period values, and arguments. Every sentence adds useful information without 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?

Since there is no output schema, the description responsibly documents the return structure and summary fields. It also covers constraints (5 ticker limit, period enum, downsampling) and the intended charting use case, making it complete for a read-only historical data 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?

With 0% schema description coverage, the description fully compensates: it documents comma-separated tickers with a max of 5, the period lookback values, and the default period of 'ytd'. This adds real meaning beyond the bare input schema.

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 opening sentence states exactly what the tool does: returns historical daily closing prices for stocks or ETFs, with a clear limit of up to 5 tickers. This distinguishes it from siblings like get_stock_quotes (current quotes) and other asset-class historical tools.

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 clearly implies use for historical daily price series and charting, and it explains the tuning knobs (period, tickers). It does not explicitly name alternatives or state when not to use it, but the context is strong enough for an agent to select it correctly.

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