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

With no annotations, the description carries the full behavioral burden. It usefully discloses that the tool is read-only and enumerates the counters returned, but it does not explain aggregation scope, time range, freshness, permissions, or what happens when a campaign has no calls.

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?

The description is compact and front-loaded with 'Call counters:' followed by the relevant metric list. Given that no output schema exists, every listed counter earns its place, and there is no redundant prose.

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 simple one-parameter read tool with no output schema, listing the returned counters is valuable and makes the response shape largely clear. The main omission is campaign-scoping language and differentiation from sibling stats tools, but the core information needed to invoke it is present.

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 100%, and the single id parameter is already documented as a campaign UUID from list_campaigns. The description adds no parameter-specific meaning beyond the schema, so the baseline of 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 clearly identifies the resource as call counters for a campaign’s phone stats by listing the exact metrics returned. It does not explicitly distinguish this from neighboring stats tools such as get_campaign_email_stats or get_phone_channel_stats, so it is clear but not fully differentiated.

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 description provides no when-to-use guidance, prerequisites, or comparison to sibling tools. It only states 'Read-only,' leaving the agent to infer that this is for campaign-level phone statistics rather than channel-level or individual-call data.

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