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

Annotations already cover read-only/idempotent/non-destructive, so the bar is low, and the description goes well beyond them by describing failure semantics ('any failure in plain words with a next step'), read timestamps, grouped ownership counts, and metric snapshots.

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?

A single front-loaded sentence leading with the core fetch, followed by a dense but purposeful content list and the sibling routing at the end. No filler, though the list is packed tightly.

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?

No output schema exists, so the description carries the return-shape burden and does so thoroughly, covering results, timestamps, status breakdown, grouped counts, failures, and snapshots — enough for an agent to call and interpret confidently.

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 both params (brandId, campaignId) are documented in the schema with their sources, so baseline 3 applies; the description adds only 'one campaign's' scoping, no extra parameter meaning.

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 ('Fetches one campaign's latest results') and enumerates the contents returned, so an agent can tell it apart from sibling getters like get_brand_brief 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 routes to the alternative: 'For the whole brand in one call, use get_brand_brief instead.' Clear selection condition, though no other when-not guidance (e.g., staleness or refresh expectations) is given.

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