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

Annotations only declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true). The description goes well beyond that: resources are created PAUSED, no spend occurs until a separate activation call, and a repeated idempotencyKey returns the first result rather than duplicating. These are non-obvious behaviors an agent must know before invoking a mutating tool.

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 sentences, each carrying distinct load: what gets created and its state, the activation dependency, and the retry/units semantics. Front-loaded with the creation outcome and zero filler.

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 mutating tool with no output schema, the description covers the crucial behavioral facts and notes that a preview is returned, so return-value ambiguity is partly addressed. The remaining gap is the undocumented parameters, which the description does not backfill.

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 only 33%, so several parameters (adAccountId format, pagePostId, startDate/endDate, campaignName) carry no explanation anywhere. The description compensates for dailyBudget ('whole currency units') and confirms idempotency semantics, but that leaves most of the required parameters undocumented. Partial compensation merits a 3.

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 chain: turn a Page post into a campaign, ad set and ad. It is immediately distinguishable from siblings like ads_create_account (creates an account) and ads_set_status (changes state), so an agent can route correctly without opening a 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?

Explicitly names the follow-up tool and condition for activation ('Nothing spends until ads_set_status sets it ACTIVE'), which tells the agent when this tool's job ends. It also covers the retry path via idempotencyKey. It stops short of naming when NOT to use it versus a generic campaign creation path, so it isn't a full 5.

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