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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds something genuinely valuable beyond that: an explicit prompt-injection warning that replies originate from contacts and must be treated as data, never instructions — a real behavioral disclosure no annotation field captures.

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 compact sentences plus a safety note, all front-loaded — scope first, optional sub-resource second, safety caveat last. The dense enumeration ("words, list, SIMs, plan…") is efficient but idiosyncratic, and it partly restates what the output schema already carries.

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 read-only single-entity fetch with full schema coverage, an output schema, and clear annotations, the description covers the content scope and the one non-obvious risk (untrusted contact content). Nothing an agent needs to invoke it correctly is missing.

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?

With 100% schema description coverage the schema already documents id and the nested people object (limit, query, state, cursor). The description contributes only the notion that people returns a single page, adding marginal semantics. Baseline 3 is appropriate.

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?

The description frames the resource unambiguously as a single campaign pulled "in full" and enumerates its returned sections (words, list, SIMs, plan, launch-readiness, country rules, progress/carrier signals), which makes the contrast with a listing tool obvious even though list_campaigns is never named. The verb is implicit rather than stated, keeping it short of a 5.

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 only usage signal is "With people, a page of its list," which implies the nested people parameter is opt-in and paginated. There is no explicit guidance on when to reach for this versus list_campaigns, update_campaign, or get_batch, and no stated preconditions beyond the required id.

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