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

Annotations already cover readOnly, idempotent and non-destructive, so the bar is lower. The description adds useful non-annotation context: the price is derived from the file itself (size, and for video length and frame rate), so the file is read first, and it discloses what the call returns (coins, balance, output size, offered targets).

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?

Front-loads the core purpose, then flows logically through cost semantics, return values, handoff and prerequisites. Sentences are short and mostly earn their place, though the parenthetical gloss and the return-value sentence are slightly more than strictly needed given the output schema exists.

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 annotations, an output schema and full schema coverage all present, the description only needs to supply the missing context, which it does: pricing model, free/non-mutating nature, prerequisite import step, and the handoff to upscale. Nothing an agent needs to call it correctly is absent.

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%, so all four parameters are already documented, giving a baseline of 3. The description adds only marginal meaning, explaining why file characteristics drive the price rather than clarifying the parameters themselves.

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 (price/estimate) and resource (upscaling an image or video) with a clarifying gloss on what an upscale is. It distinguishes itself from the sibling 'upscale' by explaining it computes a cost rather than performing the operation, and names the coin-passing handoff between the two.

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?

Explicitly routes the agent: pass returned coins to upscale as expected_cost, and states the prerequisite 'the file must be hosted: import_media first'. It also declares it is free and changes nothing, which clarifies when it is safe to call. It does not, however, differentiate itself from the lookalike sibling app_upscale_quote.

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