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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds substantial behavioral context beyond them: fixed pages of up to 20, oldest-first ordering, one Scan spanning pages, metric=null for fact-backed Scans with no displayed brands, total/totalScans counting semantics, Share of Voice retaining the full denominator, and no model-alias merging.

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?

Dense but front-loaded, leading with what the tool does before the parameter routing and pagination rules. It is on the long side, and the ordering/counting rules could be tightened, but each sentence carries operational information rather than 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?

For a paginated, trend-reading tool with an output schema and strong annotations, the description covers everything an agent needs: correct ID source, pagination/continuation semantics, ordering, null-metric handling, and restart conditions. Despite the output schema existing, it also usefully explains key field meanings.

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 100% so the schema documents all three parameters, but the description adds meaning: it clarifies that resultId is the collected result ID (not promptId) and defines cursor continuation rules. This is value beyond the structured fields, though the schema already carries the base definitions.

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: reading how the exact question, saved model, and region behind one collected result changed across completed eligible Scans. It explicitly distinguishes itself from get_prompt_results ('Full answer text is in get_prompt_results'), so an agent can route correctly without opening a schema.

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 tells the agent to pass resultId from get_prompt_results, not a prompt ID, and to follow nextCursor with unchanged siteId/resultId. It also states when-not and restart conditions ('new Scans do not extend continuation', 'Restart after historical evidence or anchor edits', 'No limit argument or Scan launch').

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