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

Annotations already declare destructive/openWorld/non-idempotent, but the description adds substantial context beyond them: 'not retried server-side', 'pass distinct content per call', the 402 entitlement failure mode, and the free-cost model (no credits, provider seat applies). This is exactly the kind of live-side-effect warning an agent needs before invoking.

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 the core action and asset requirements before timing and caveats; every sentence carries distinct information and nothing is redundant. It is dense and a bit long, but the length is justified by the tool's 15-param complexity.

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 15-param, nested-object tool with no output schema this covers the critical call-path decisions (assets, timing, entitlement, side effects) well. It falls short only on the optional fields (per-account variants, platform overrides, visibility/draft), which remain undocumented.

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 0% across 15 parameters, so the description carries the burden. It well explains assetKind conditionality (video→videoUrl, photo/carousel→photoUrls, 2+ = carousel), scheduledAt, and addToQueue, but says nothing about tags, title, caption, visibility, saveAsDraft, thumbnailUrl, accountVariants, or platformOverrides (including the first_comment override). High-value partial compensation, but clear remaining gaps.

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 ('Publish or schedule a post') plus scope ('one or more connected accounts on a brand ... multi-platform fan-out in a single call'). An agent can immediately distinguish this fan-out publish from siblings like cancel_social_post, retry_social_post, or publish_to_managed_account.

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 explicit routing for the three timing modes (omit both = publish now; scheduledAt = specific time; addToQueue = auto-slot) and flags them as mutually exclusive. It also names the upstream alternatives (get_video outputUrl, import_asset_from_url, create_upload) for sourcing the asset URL.

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