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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's value-add is real: it discloses pagination size (25 per page), where the total lives (meta.total_count), ordering (newest first), and an exclusion contract ('Contacts and their phone numbers are not included'). This is concrete behavioral context beyond the annotations.

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 sentences that are front-loaded with the core action and then packed with useful facts; the parenthetical clarifications earn their place. Slightly dense in the second sentence, but no 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?

With no output schema and only 2 params, the description covers what an agent needs to interpret results: ordering, page size, total-count location, enumerated statuses, direction semantics, and what is omitted. The only gap is the meaning/effect of the 'fields' and 'page' parameters.

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 only 50%: 'fields' is documented in the schema, but 'page' carries nothing beyond minimum:1. The description compensates for pagination implicitly (25 per page, meta.total_count) but never explains what 'page' does or how 'fields' affects the response, leaving the low-coverage parameter under-specified.

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 ('List the voice campaigns of this account') plus scope details: sort order, page size, and what each record contains. The 'voice' qualifier distinguishes it from list_campaigns and list_whatsapp_campaigns in the sibling set without opening either 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?

Usage is implied by the account-scoping statement, and the note about contacts/phone numbers not being included hints at when a different call (e.g. get_voice_campaign or list_calls) is needed. However, no sibling is named and there is no explicit when-to-use/when-not guidance for choosing among list_campaigns, list_whatsapp_campaigns, and get_voice_campaign.

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