list_extensions

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

No annotations are present, so the description carries full responsibility for behavioral disclosure. It explains the core scoping behavior between the two campaign_id states, which is valuable. However, it never signals that this is a non-destructive read operation, nor does it mention return format, pagination, or the fact that it aggregates multiple extension types into one response.

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 compact sentences, front-loaded with the resource name and immediately followed by the key scoping rule. The colon usage is slightly unconventional but functionally clear. No wasted words; every sentence carries meaningful 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?

For a simple one-parameter list tool, the description covers the critical scoping logic comprehensively. The only omission is the return format, which is somewhat mitigated by there being no output schema. Given the tool's low complexity, this is reasonably complete, though a brief note on the returned extension structure would fully close the gap.

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 compensate, and it does: it assigns behavioral meaning to the single parameter, clarifying that null means 'full account library' and a set value means 'only extensions associated with that campaign.' This goes well beyond the schema's bare 'Campaign Id' field, providing precisely the disambiguation an agent needs.

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?

The description identifies the resource (ad extensions) and concisely describes the two distinct behaviors based on campaign_id: a full account library versus campaign-scoped results. The verb 'list' is implied from the name rather than stated explicitly, and example extension types ('sitelinks, callouts, structured snippets') help clarify scope, which reasonable disambiguates it from mutation siblings like remove_extension and create_callouts.

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?

The description clearly explains the two calling modes (campaign_id=None vs set), which serves as effective usage context for a single-parameter listing tool. However, it provides no explicit when-not-to-use guidance or mention of alternatives, relying on the mode distinction to implicitly convey when each call form is appropriate.

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