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

With no annotations, the description carries the full burden. It clearly signals a read-only operation via 'Retrieve' and discloses the specific data points returned, which is useful. It does not explain return structure, status value semantics, error behavior, or how optional filters affect results, but for a simple read tool the core behavior is reasonably transparent.

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?

A single sentence that is front-loaded with the verb and resource, and lists the returned metrics without waste. Every word earns its place.

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 low-complexity tool with all parameters documented in the schema, the description is nearly sufficient: an agent knows the required parameter and what data will be returned. The lack of any output schema or mention of return format/status conventions leaves some ambiguity, but the gaps are not severe enough to prevent correct invocation.

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 description coverage is 100%, so the description need not reiterate parameter details. The phrase 'for a campaign' correctly maps to the required campaignId, but the description adds no extra meaning about agentId or accountId filtering beyond what the schema already states.

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 uses a specific verb ('Retrieve') with a clear resource ('delivery status... for a campaign') and enumerates the exact metrics returned (sent, delivered, read, failed). It is clearly scoped to a single campaign, though it does not explicitly distinguish itself from siblings like get_campaign_performance or get_message_stats.

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 implies the tool is for checking campaign delivery metrics in real time, which gives reasonable context for use. However, it does not state when to prefer this tool over similar siblings, nor mention any exclusions or alternative routing.

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