search_ads

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

Discloses key behaviors: returns specific fields, supports loading 50+, paginates by scrolling, fetch_reach makes additional requests (slower), eu_total_reach null for non-EU ads (Meta's design). No annotations provided, but description fully covers safety and performance traits.

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 purpose and capacity. Parameter details follow in structured list. Slightly verbose but each sentence provides value. Could tighten the return format description, but overall well-organized.

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?

Given no output schema and 0% schema coverage, the description thoroughly covers all needed context: parameter semantics, return structure, behavioral notes (paginate, slow fetch_reach), and even references sibling tool. Edge cases (null reach) are explained.

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 has no parameter descriptions (0% coverage). Description fully compensates with detailed explanations for all 4 parameters: keyword, country (with ISO-2 and 'ALL'), limit (pagination), fetch_reach (slower, use for ≤50). Also clarifies return format and edge cases.

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?

Clear verb 'search' + resource 'Meta Ad Library' with keyword. Mentions returns advertiser + description and capacity (50+). Distinguishes from sibling get_ad_details by scope (multiple vs single ad).

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 explains when to use (search by keyword) and when not to (use get_ad_details for a single ad's reach). Provides parameter usage details: keyword free-text, country ISO-2 with 'ALL' no filter, EU for reach, limit with pagination, fetch_reach slower for ≤50.

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