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

Annotations (readOnlyHint, idempotentHint, destructiveHint=false) already cover the safety profile, and the description is consistent with them by framing this as a free drafting step. It adds genuinely useful context beyond the annotations: 'Costs no credits' and detailed OAuth/API-key auth instructions with a concrete header format and settings URL.

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-loaded with purpose and output shape, then workflow, then auth. Every sentence carries load, though the trailing auth block is dense and could be split for readability. Still efficient overall.

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?

An output schema exists, so return values need not be explained; the description instead covers the input artifact, the downstream workflow, and the sign-in prerequisites. Nothing an agent needs to call this tool correctly 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 description coverage is 100% and the single nested 'brief' object enumerates its fields (brandName, valueProps, shotCount, aspect, etc.) in the schema itself. The description describes the output shape rather than adding input meaning, so the baseline 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 verb and resource (turn an ad brief into a storyboard) and immediately defines the produced artifact: 1-5 shots with framing, spoken line, caption, duration. It also names the sibling tools that follow it in the workflow (estimate_ad_cost, generate_ad), so an agent can place it precisely in the pipeline.

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?

Explicit when-to-use and sequencing: show the storyboard to the person, edit if needed, then price with estimate_ad_cost and submit with generate_ad. This routes the agent to the correct alternatives and states the ordering constraint rather than leaving it to inference.

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