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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered structurally. The description adds value by disclosing that duration is measured from video_url and that the estimate spans the full dubbing pipeline, which annotations cannot convey.

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 with the core purpose front-loaded and the input guidance following. No filler; every clause carries information.

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 at least names the return unit (credits). For a 4-parameter tool with sparse schema descriptions it covers the main input paths, though source_language remains unexplained.

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 only 25%, so the description must compensate. It usefully explains the video_url vs duration_seconds choice and that duration is measured server-side, but leaves source_language entirely undocumented and only implicitly covers targets via 'one or more languages'.

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 (Estimate) and resource (credits to dub one video into one or more languages), and enumerates the underlying pipeline (speech-to-text + translation + voice + video merge). It is clearly a cost-preview step distinct from the sibling localize_video that actually performs the operation.

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 positions itself as a pre-flight step: 'before running localize_video', naming the alternative it precedes. It gives clear context for when to reach for it but does not state any when-not conditions.

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