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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered; the description adds the meaningful behavioral fact that blocking is account-wide rather than per campaign. It stops short of saying what a returned entry looks like (date only, or date plus label), which is the remaining 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 tight sentences: definition first, then the use case, then the disambiguation. Every sentence carries information an agent would otherwise have to guess.

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 zero params, rich annotations and no output schema, the description covers what an agent needs to decide to call it and what the data means. The only missing piece is the shape of the returned entries, which is a minor omission for a simple date list.

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?

The tool takes no parameters and the schema is an empty object with additionalProperties false, so there is nothing to disambiguate. Baseline 4 applies; the description correctly implies an unfiltered full listing rather than a lookup by date.

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?

Defines the resource precisely: dates on which no campaign sends anything, covering public holidays and company shutdowns, scoped account-wide. It also separates itself from per-campaign scheduling settings held in `campaign_update`, so an agent can distinguish it from that sibling without opening schemas.

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 trigger — 'Read this when a user asks why nothing sent on a particular day' — and redirects the adjacent question (weekly sending window, timezone) to `campaign_update`. That is explicit when-to-use plus a named alternative.

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