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

The description goes beyond the readOnlyHint annotation by disclosing that some numbers may lag and that caveats must be read before making operational conclusions. This adds valuable behavioral context about data freshness, which is not captured in annotations or schema. No contradiction with annotations 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 sentences, no fluff. The first sentence front-loads the core purpose and metrics, while the second delivers an essential caveat about lag. Every word adds value, and the structure is highly scannable.

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?

Given the lack of an output schema, the description does a good job listing the key fields in the response (leads, messages, replies, etc.) and warns about lag. It omits details on pagination behavior or how status filters work, but these are partially available in the schema. Overall, it covers the critical user decision needs for a read-only reporting tool.

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 only 50%, with limit and offset lacking any description. The description mentions campaign_id behavior ('Omit campaign_id to list every campaign') but this is redundant with the schema's own description. It provides no additional meaning for limit, offset, or status, leaving half the parameters semantically 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?

The description uses the specific verb 'Report' and clearly identifies the resource ('what a campaign has actually done') with a concrete list of metrics. It distinguishes itself from sibling tools by emphasizing post-launch actuals (leads, messages, replies) rather than pre-launch readiness or lead sources. Including the instruction to omit campaign_id for listing every campaign further clarifies its scope.

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 clear context for when to use the tool—when you need a report on campaign performance—and instructs to omit campaign_id for a full account view. However, it does not explicitly state when not to use it or name alternative tools, leaving some ambiguity versus siblings like review_campaign_readiness or get_interested_leads.

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