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

Annotations already declare destructiveHint=true and openWorldHint=true, so the safety profile is known; the description adds value beyond that by disclosing the ISO 8601 format requirement and the confirm=true gate tied to clear_end. It still doesn't say whether confirm is needed for ordinary date changes, how existing schedules are overwritten, or any timezone handling – gaps that matter for a destructive mutation.

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?

Two sentences, front-loaded with the core action and followed by the single non-obvious rule. Every clause earns its place and there is no redundant restatement of the title or annotations.

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 9-parameter destructive mutation with no output schema, the description covers the biggest trap (clearing an end date without confirm) but omits target resolution (id_or_name plus level/folder/account) and the result of the call. Adequate but with clear gaps an agent would have to guess at.

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 33%, so the description must carry weight; it explains start_time/end_time format and the clear_end/confirm interplay well, but the two required parameters (level, id_or_name) and how folder/account disambiguate the target are left entirely to the schema. Partial compensation justifies the baseline 3 rather than higher.

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 ("Set") and resource ("start and/or end time ... of a campaign or ad squad"), which cleanly separates it from sibling mutators like snapchat_update_budget, snapchat_update_bid, and snapchat_rename. It does not name any sibling explicitly, so it stops short of a 5.

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?

The clear_end sentence implies a usage condition ('removes the end date – runs until paused') and gates it on confirm=true, which is genuinely actionable. However there is no explicit statement of when to use this versus pausing (snapchat_set_status) or removing (snapchat_remove), and no prerequisites or scope caveats.

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