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

Annotations only declare the generic write/open-world profile (readOnlyHint=false, destructiveHint=false). The description adds meaningful behavior: it impacts the live account, the created ad defaults to PAUSED, and it enforces a confirm:true safety gate. That said, 'PAUSED default' and 'confirm' partly overlap with schema descriptions, so it is strong but not fully additive.

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?

A single front-loaded sentence opens with the [WRITE — changes your live account] warning, then delivers scope, precondition, default state, and the confirm requirement with zero wasted words.

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?

With no output schema, the safety annotations present, and full schema coverage, the description supplies everything an agent needs: purpose, write impact, precondition, default status, and the confirm gate. Nothing required 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 description coverage is 100%, so all five parameters (including post_id format and ad_set_id provenance) are already documented in the schema. The description corroborates 'existing ad set' and 'confirm:true' but adds no syntax or semantic detail beyond the schema — the baseline 3 applies.

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 (promote/boost), resource (existing Facebook Page post as an ad), and the key scoping distinction '(no upload)' plus 'under an existing ad set'. This clearly separates it from the sibling meta_ads_create_image_ad without needing to open 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?

Implies the preconditions that an ad set must already exist and that the post already exists (no upload path), steering the agent away from the create/upload siblings. However, it never names an alternative tool or an explicit when-not-to-use condition, so it falls short of full routing guidance.

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