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

Annotations cover the safe-read profile, but the description adds substantial non-obvious behavior: when the identity directory is unreadable it silently falls back to identities from existing ads (source="existing_ads"), and those IDs still work in create_tiktok_ad except the display name is missing. This is exactly the kind of behavioral disclosure annotations cannot convey.

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 front-loaded sentences with no wasted filler; the primary purpose precedes the fallback caveat. The parenthetical Meta analogy earns its place for cross-platform agents, though the sentence runs long.

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 an output schema present, return-value detail is not needed, and the description covers purpose plus the important fallback path. The one remaining gap is input-parameter meaning, which leaves the tool slightly under-specified for its single argument.

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 0% and the sole parameter advertiser_id is never mentioned in the description — not its meaning, nor that it is optional (default ""). The description compensates for none of the parameter gap, and the 'source="existing_ads"' reference describes output, not the input parameter.

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+resource ('Lists TikTok ad identities') and immediately explains the role it plays — supplying the identity_id required when creating ads, with a cross-domain analogy (Meta's page_id). An agent can tell what it produces and why, distinct from create_tiktok_identity or list_tiktok_ad_accounts.

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 frames usage via 'the identity_id needed when creating ads is obtained here,' effectively routing the agent to call this before create_tiktok_ad. It also explains the degraded-mode branch, though it does not name an alternative tool or state explicit exclusions.

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