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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces this with 'Nothing is created or charged. Free.' while adding genuinely new behavior: it returns the maximum credits committable, the balance required, whether balance and the key's daily cap cover it, and when the charge would occur. That is substantive disclosure an agent could not get from the annotations or schema.

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?

Purpose is front-loaded in an imperative clause, followed by usage, then return values — a sensible order. It is dense and slightly run-on in the returns sentence, but every clause carries information; there is no 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, an accurate description of the return fields is essential and is provided in detail (max credits, required balance, coverage verdicts, charge timing). For a zero-required-parameter, read-only estimation tool, nothing an agent needs in order to call it or interpret the result is missing.

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 100%, so baseline is 3, but the description adds real semantics: it explains how `tool` and `arguments` compose as a hypothetical replay of a future call, and clarifies that `draftId` is a shortcut equivalent to {tool: 'autoshort_render_draft', arguments: {draftId}}. That contract between the parameters is not obvious from the nested schema alone.

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 and resource: price/estimate the cost of a paid tool call before executing it, and names the priced tools (autoshort_generate_video, autoshort_render_draft, autoshort_ugc_render_batch). It does not explicitly distinguish itself from sibling quoting tools like autoshort_quote_video or autoshort_quote_character_episode, which is the only missing piece for a 5.

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?

Clear temporal guidance — call this BEFORE making the paid call — plus a concrete invocation recipe ({tool, arguments} or the {draftId} shortcut). It stops short of naming when to prefer a sibling quote tool instead, so the routing vs. alternatives is only partially resolved.

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