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

Against annotations that only flag destructiveHint and openWorldHint, the description adds substantial behavioral context: editor access requirement, native last-write-wins semantics, the instruction to re-read setup after ambiguous outcomes, reuse of campaignId on retry, exact minor-unit amounts governed by the setup budget policy, and confirmation that saves never touch live campaigns or call Google Ads. It also states explicitly that discard cannot be undone, which sharpens the destructiveHint rather than contradicting it.

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?

Very information-dense with little waste, but the structure is poor: it opens with access requirements and return-value plumbing ("Returns the current draft summary in data and the native operation response in stepResult") before stating what the tool does, and inline brace notation for payloads is harder to parse than prose or a short list. It reads as one compressed block rather than a front-loaded purpose followed by usage details.

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 an 11-parameter, 9-action tool with nested objects, the description covers access, ordering, save semantics, retry behavior, irreversible discard, and the launch boundary. An output schema exists so return values need not be re-explained, and the brief data/stepResult mention is tolerable overhead. The remaining shortfall is that per-action parameter requirements (which fields each action accepts, and the dual minor-unit fields) are only partially mapped.

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 0%, so the description carries the full burden and mostly meets it: it spells out the payload shapes for contentSave, locationSave (including both GLOBAL and COUNTRIES modes), adCopySave (assisted|preserve) and budgetSave, and ties expectedUpdatedAt to the inspect output and userIntentSummary to discard. It leaves gaps on artistId and on the coexistence of budgetAmountCents and budgetAmountMinor, where an agent still cannot tell which integer field to populate when currency differs from the artist default.

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?

The description names the resource (YouTube draft) and enumerates the concrete operations the action parameter exposes: setup, videos, screen, save_content, save_location, save_ad_copy, save_budget, inspect, discard. It also draws a boundary against the sibling launch flow ("Draft saves never launch... launch is a separate step"). The framing is telegraphic rather than declarative, so an agent must reconstruct the overall purpose from the action list rather than reading a single clear statement of it.

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?

Gives real sequencing guidance: read setup first, browse with videos/pageToken, screen with videoId, then save per-section payloads. It also imposes an explicit precondition on the riskiest action: "Use discard only on explicit user request with campaignId, expectedUpdatedAt from inspect and userIntentSummary." No guidance is offered on when to choose this tool over adjacent campaign tools such as dynamoi_get_campaign or dynamoi_manage_smart_campaign_creative, so it stops short of full sibling routing.

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