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

Annotations already declare the safe read-only, idempotent profile, so the bar is lower, yet the description adds real behavioral context: results carry PII, the return is bounded, there is a hard cap of 1000, and a `truncated` flag signals truncation. This is exactly the kind of beyond-annotation disclosure the tool needs.

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?

Front-loaded with the core purpose, then constraints in roughly four dense sentences with no filler. The mode/parameter clauses are packed tightly but remain readable and every sentence carries information.

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 values need not be detailed, and the description still flags the `truncated` semantics. Given 0% schema description coverage across 7 parameters, the near-complete parameter coverage makes this adequate; only advertiser_id is unaddressed.

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 0%, so the description must carry the load, and it does: it explains lead_source values, the page_id requirement conditioned on INSTANT_FORM, ad_id narrowing, the YYYY-MM-DD date format, and the limit hard cap of 1000. Only advertiser_id is left unexplained, a minor gap against 7 parameters.

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 ('Downloads the actual leads collected by TikTok lead-gen or messaging ads') plus the differentiating detail 'with each lead's answered fields'. This clearly separates it from siblings like list_tiktok_lead_forms (enumerates forms) and get_tiktok_lead_form_fields (enumerates field definitions).

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 routes between the two modes: INSTANT_FORM requires page_id sourced from list_tiktok_lead_forms, while DIRECT_MESSAGE covers messaging ads, and ad_id narrows to a single ad. It gives selection conditions but no explicit 'when not to use this' or comparison against download_meta_leads/download_linkedin_leads.

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