verify_emails

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

There are no annotations, so the description carries full burden. It discloses that the tool consumes credits, which is a useful behavioral trait. However, it doesn't disclose what happens for invalid addresses, whether results are returned synchronously, whether there's a rate limit, or what statuses outcomes can take. For a credit-consuming tool with zero annotation coverage, this is a significant gap.

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, front-loaded with the core action and a cost caveat. Efficient and to the point. It could add a bit more behavioral detail without bloating, but as-is it's appropriately sized.

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 2-param tool with no output schema and no nested objects, the description is reasonably adequate. The key missing piece is behavioral detail — lack of any note about response format or outcomes given there's no output schema and no annotations to lean on. The credit cost is disclosed, which matters, but return-value expectations are unspecified.

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% — both 'email' and 'emails' have descriptions, and the schema notes the 20-item max and the OR relationship between the two. The description adds nothing beyond schema, so baseline 3 is appropriate. No param info in description to elevate it.

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+resource ('Verify email deliverability') and scopes to 'one or more email addresses.' The purpose is clear, though it doesn't explicitly differentiate from siblings, all of which are unrelated tools (leads, deals, campaigns), so differentiation is implicitly obvious.

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 adds 'Consumes verification credits,' which is a meaningful cost signal for when to use. However, it provides no guidance on when not to use it, no criteria for choosing single vs batch, no alternative tools (e.g., a cheaper or bulk option), and no stated preconditions for verification. For a paid/credit-consuming operation, this is an incomplete guidance picture.

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