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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds real value by enumerating the returned values (fee breakdown, payout, profit, margin, ROI, official fee source, calculator link) in the absence of an output schema, and by asserting parity with the official Fliprofit calculators.

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?

Two sentences, front-loaded with the core purpose before the platform list and return values. The parenthetical platform run is long but informative rather than redundant; nothing is filler.

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 usefully names every returned field, and the input schema fully documents all eight parameters including the complex nested options object. The only meaningful gap is the absence of guidance on when to prefer compare_platforms.

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 100%, including a detailed enumeration of the nested platform-specific options object, so the schema carries the full parameter burden. The description adds no meaning beyond what the schema already states, making baseline 3 correct.

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 ('fees, payout and profit for one sale on one platform') and enumerates all twelve supported platforms, so the scope is unmistakable. The output fields listed (fee breakdown, payout, profit, margin, ROI) further pin down what the tool produces.

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 'one sale on one platform' phrasing implies usage, and 'Same numbers as the Fliprofit calculators' establishes authority, but there is no explicit routing guidance. The sibling compare_platforms is the obvious alternative for multi-platform scenarios and is never mentioned, leaving the agent to infer when to switch.

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