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

Annotations only declare it is a non-read, non-destructive, closed-world write. The description goes well beyond that by disclosing partial-failure semantics ('platforms that can't take the upload's content type come back with ok: false') and a full per-platform content-type matrix, which is the main failure mode for a batched write. It stops short of stating permissions/account requirements or whether successful drafts are later publishable, keeping it at 4 rather than 5.

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 the sibling comparison in the first two sentences; the content-type matrix follows as reference material. The enumerated platform list is dense prose that would read better as a table, but every clause carries actionable constraint 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?

No output schema exists, and the description compensates by explaining the return shape (per-platform results with each post's id and ok flags). For a 3-parameter batch write with full schema coverage, nothing an agent needs in order to call it 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 coverage is 100%, so the baseline is 3, but the description adds real meaning for the 'platforms' parameter: the accepted content types per platform and the Snapchat Spotlight video-only caveat constrain which values will succeed. Idempotency and video_upload_id semantics are left entirely to the schema.

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 ('Creates draft video posts') plus the distinguishing scope ('for multiple platforms in a single call'). It explicitly separates itself from the singular sibling create_post_draft, so an agent can route without opening either schema.

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 an explicit selection rule: 'Equivalent to calling create_post_draft once per platform but batched — use this instead when drafting to more than one platform.' The alternative and the condition that selects it are both named, leaving nothing to inference.

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