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

Adds real behavior beyond the annotations: the ad is created in PAUSED state, ad type is inferred from the creative rather than chosen, and the ad enters Snap review. These are exactly the facts an agent needs to avoid assuming a live ad. It omits permission requirements and never mentions the dry_run option despite its availability.

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?

Three short sentences, front-loaded with the core action and the PAUSED default, then the auto-matching behavior, then the review caveat. No filler and no repetition of the title.

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 creation tool with no output schema and openWorldHint, the description covers the key lifecycle facts (paused, auto-typed, reviewed) but omits what the call returns (e.g., new ad ID) and how dry_run/language affect behavior. Adequate but with clear gaps for a 7-parameter mutation.

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 57%, and the description does not add meaning for the uncovered parameters. creative_id and adsquad are only implied through prose, while dry_run and name are undocumented in both the schema and the description — the missing dry_run guidance is particularly consequential for a create operation.

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 ("Create an ad") plus the exact container ("in an ad squad from an existing creative"), which cleanly distinguishes it from snapchat_create_creative, snapchat_create_adsquad, and the read-only snapchat_ads/snapchat_creatives siblings it cites.

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 the prerequisite chain clearly: the creative must already exist (see snapchat_creatives or snapchat_ads) and the ad lands inside an existing ad squad. It does not explicitly state when NOT to use it (e.g., when a duplicate would do), so it stops short of full alternative routing.

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