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

Annotations already declare readOnlyHint and openWorldHint; the description adds real context beyond them — the grid is bounded by the earliest expiry, and calculatorUrl implies an external dependency on optionsprofitcalculator.com. It does not mention computation cost or how large the returned grid can be, which is a minor gap.

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?

Three short sentences, front-loaded with the differentiator ('Everything probability_of_profit returns, plus...') then the use case, then the calculator URL note. Slightly dense opening clause but no wasted text.

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 7 parameters, no output schema, and coverage at 86%, the description usefully describes what comes back (P/L grid plus calculatorUrl) and the graph's date bound. It leaves return shape details (grid size, units per cell) unspecified, but the essential calling information is present.

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 86%, so the schema already documents nearly every parameter and default. The description only indirectly touches priceMin/priceMax via the 'grid of stock prices' wording and the earliest-expiry cutoff; it adds no syntax or default detail beyond the schema, so baseline 3 applies.

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 computation ('P/L in dollars across a grid of stock prices and dates up to the earliest expiry') and explicitly positions itself as a superset of probability_of_profit, so an agent can distinguish it from all siblings without opening a schema.

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 clear usage contexts ('chart a position', 'see how profit changes over time') and implies the lighter sibling probability_of_profit when only POP data is needed. It stops short of an explicit 'use X instead when...' exclusion, so it is strong but not complete routing guidance.

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