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

Beyond the annotations it adds two pieces of context the structured fields don't carry: the operation is "Free" (cost implication) and it does not build anything, only produces titles/summaries. "Returns idea ids" also clarifies this is a generative step that yields handles rather than a persisted carousel, consistent with readOnlyHint=false. It does not say how long idea ids remain valid or whether they are reusable, leaving a modest gap.

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?

Three short sentences, with the core action first and the chaining hint last. Nothing is repeated from the title, and every clause carries new 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 9 all-optional parameters and no output schema, the description steps in to describe the return value (titles, summaries, idea ids) and its downstream use, which is the most important missing structured info. It does not explain what happens with defaulted params like mode or niche, but that is largely covered by the schema itself.

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% and each of the 9 parameters already has a substantive description (language override, value vs promo mode, count range, niche ids from list_options). The tool description adds no parameter-level meaning beyond that, so baseline 3 applies.

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 ("Brainstorm carousel ideas (titles + summaries)") and immediately delimits scope with "without building them," which separates it from build_carousel and create_carousel in the sibling list. It also names the downstream consumer, so the agent knows exactly which tool the output feeds.

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 phrase "without building them" plus "Returns idea ids that build_carousel accepts" gives clear routing: use this to ideate, then hand ids to build_carousel. It does not explicitly state when *not* to use it (e.g. when an existing carousel should be edited instead), so it stops short of full when/when-not guidance.

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