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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description adds real value: it discloses the returned fields (events, optimization_event, activity_status, setup_mode) and, critically, an API limitation — that raw 7/28-day fire counts are unavailable via the Marketing API and live in Events Manager.

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 what it lists, then the return contents, then usage, then the limitation — every clause carries information and nothing is padded. Parentheticals (ON_WEB_REGISTER, SHOPPING, FORM) are illustrative value, not filler.

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?

An output schema exists, so return values need not be documented, yet the description still clarifies the key fields. Together with the disclosed limitation, an agent has everything needed to select and call it correctly.

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% and the description never mentions advertiser_id, so it adds no parameter meaning. With a single common identifier parameter, the gap is minor but the description does not compensate.

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 conversion pixels") and immediately scopes it to measurement/WEB_CONVERSIONS/CONVERT optimization. Distinguishes it from siblings like create_tiktok_pixel and list_tiktok_bc_pixels by naming its domain of use.

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 a concrete use case: "verify a conversion (e.g. signup) is set up before optimizing an ad group for it." That tells the agent when to reach for this tool, but it names no explicit alternative and states no exclusions.

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