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

Annotations already declare readOnlyHint=true, non-destructive, open-world, so safety is covered. The description adds real value beyond that by naming the endpoint (GET /v1/campaigns/{campaignId}) and listing the returned fields, which matters because no output schema exists.

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 short sentences with no filler and the returned-field summary front-loaded. The telegraphic fragment style is efficient but slightly sacrifices readability (e.g., 'send ids' is unexplained).

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 one-parameter read tool with annotations and no output schema, the description covers what is fetched and roughly what comes back. Only minor gaps remain, such as error/not-found behavior and any permission requirements.

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?

Only one parameter and schema coverage is 100%, so the schema already documents campaign_id with type, pattern, and length bounds. The description conveys nothing extra about the id format or source (path parameter in the endpoint string is the sole addition).

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 resource (one campaign) and enumerates what it returns: state, kind, blacklists, send ids, sent date. 'One campaign' implicitly distinguishes it from list_campaigns and get_campaign_report, though no sibling is named.

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?

Usage is only implied — retrieve a single campaign by id. The note 'The send id is needed to see content' is a useful downstream dependency hint pointing at content-related siblings, but there is no explicit when-to-use / when-not guidance.

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