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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the scope constraint (specific domains, not bulk) and the return categories, which is useful context. However, it doesn't disclose behavior like whether multiple domains are processed in one call, error behavior, or rate limits. With annotations covering the safety profile, a 3 is appropriate – the description adds some value but not rich behavioral context.

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: the core purpose is in the first sentence, followed by clear USE FOR / DO NOT USE FOR / RETURNS sections. Every sentence earns its place, and the structure makes it scannable for an agent. No wasted words.

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 single-parameter read-only lookup tool with 100% schema coverage and annotations covering the safety profile, the description is nearly complete. It states the purpose, the alternative, and the return categories. The only minor gap is that it doesn't describe pagination or limits on the number of domains, but that is a small omission given the tool's simplicity.

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 schema already documents the 'domains' parameter with an example. The description adds that the parameter is for 'specific domain(s)' and implies the lookup scope, but doesn't add syntax or format details beyond what the schema provides. Baseline 3 is correct when the schema does the heavy lifting.

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 states a specific verb ('Get'), a specific resource ('account summary insights' for specific domains), and explicitly lists what it returns (engagement metrics, revenue data, company info). It also distinguishes itself from get_insights_report by naming the sibling and the condition that selects it. An agent can tell this apart from get_account_details and get_insights_report without opening schemas.

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 explicitly says 'USE FOR: Quick lookup of specific company information, engagement metrics, revenue data' and 'DO NOT USE FOR: Bulk analysis or complex filtering (use get_insights_report instead)'. This gives clear when-to-use and when-not-to-use guidance, and names the alternative tool. Nothing is left to inference.

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