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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=true; the description goes well beyond that by disclosing the PAUSED creation state, that no spend occurs until a separate activation, the idempotency/retry deduplication behavior, and the currency-unit convention for dailyBudget. These are exactly the behavioral facts an agent needs before invoking a 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?

Three tight sentences with zero filler, and the most consequential fact (created PAUSED, nothing spends) is front-loaded before retry and units details. Every sentence earns its place.

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 mutation with no output schema, the description covers the safety-relevant behavior thoroughly and even names the return artifact ('a preview'). Gaps remain around account/profile selection and date semantics, but those are documented in the schema descriptions the description can lean on.

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 33%, so the description must compensate for six undocumented parameters. It adds real value for dailyBudget (whole currency units, not in schema) and restates idempotencyKey semantics, but says nothing about adAccountId vs accountId/profileId selection, startDate/endDate meaning, pagePostId format, or campaignName constraints. Partial compensation only.

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 ('Turn an existing Page post into a new campaign, ad set and ad') plus the resulting state ('created PAUSED') and return ('a preview'). This clearly distinguishes it from siblings like ads_create_account and ads_delete_campaign without needing the 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 the operative condition for spending ('Nothing spends until ads_set_status sets it ACTIVE'), which routes the agent to the sibling that activates campaigns, and explains the retry path via idempotencyKey. It stops short of explicit when-not-to-use or alternative creation paths, but the activation handoff is concrete.

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