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

Annotations already declare this a safe, non-destructive, closed-world read. The description adds genuine value by disclosing the result shape (overall and per model) and an omission rule for unstated length/resolution combos, which matters because there is no output schema. It stays silent on how the optional audio/input/used/apply_deals filters narrow rows, and on what an empty result looks like.

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 tightly packed sentences with no filler. The core scope is front-loaded and the omission caveat is a single clause rather than a separate paragraph.

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 six-parameter, read-only pricing query with no output schema, the description covers scope, output granularity, and row-omission behavior, which is the important part. It leaves open whether prices are totals or per-second, what currency/plan basis applies, and whether the other filters change which rows are omitted.

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 six parameters are already documented in the schema including enums, ranges, and defaults. The description adds no parameter-level meaning beyond the phrase 'for a clip length and resolution', so the baseline of 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 resource and verb-equivalent: the cheapest *stated* VidFare price for a given clip length and resolution, returned both overall and per model. That is clearly distinguishable from get_model_prices or estimate_cost by intent, though it never names a sibling explicitly.

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?

There is no when-to-use or when-not-to-use guidance and no mention of the sibling tools (estimate_cost, get_model_prices) it overlaps with. The word 'cheapest' implies comparison shopping, but the agent must infer that this is a ranking tool rather than a cost estimator.

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