Search

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

Adds real value beyond the annotations: credit consumption, the confirm=true gate, GET-vs-POST transport behavior, and the reassurance that read-like POSTs do not publish to social platforms. It also enumerates the returned fields (ad_archive_id, page_name, is_active, publisher_platform, snapshot contents), which matters given there is no output schema. It does not cover pagination termination or rate limits.

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-loads purpose, then filters, then return shape, then transport and cost caveats. The return-field enumeration is a long run-on sentence, and the credit/confirm warning is buried at the end, but overall there is little waste.

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 14-parameter, 5-enum tool with no output schema, the description covers the essentials: what comes back, the credit gate, and the transport fallback. Remaining gaps (pagination limits, how trim changes results, exact cost) are minor relative to the schema's full parameter documentation.

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 the schema already documents all 14 parameters including enums and defaults. The description's only parameter-level addition is the 2-letter language code example, which the schema already states. Baseline 3 is appropriate.

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 with scope: 'Searches the Meta Ad Library by keyword and returns matching ads.' The keyword-based scope distinguishes it from the company-oriented siblings (facebook_ad_library_company_ads, facebook_ad_library_search_for_companies), but those siblings are never named, so the agent must infer the routing itself.

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 operational guidance (GET for normal requests, POST when the cursor grows too large) and a precondition (requires confirm=true, consumes credits), which is genuinely useful. However, it never says when to choose this tool over the other ad-library search tools or the company-ads variants, so routing guidance is only implied.

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