Many names at once

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

With no annotations, the description carries the full burden. It discloses batch capacity (up to 100), the summary return with match rate, and efficiency characteristics. However, it does not explain what happens on partial failures, what the full response shape looks like, or that values can be emails/usernames despite the type parameter.

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, both informative and front-loaded. The first sentence states capability and output, and the second gives a practical usage reason with no filler.

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?

The tool has no annotations, no output schema, and three parameters, so the description must carry more weight. It covers the core batch behavior and match-rate summary, but omits the type parameter's support for emails/usernames, the country override behavior, and a clearer picture of the response. These are useful for correct invocation but partially covered by the schema.

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 names, type, and country parameters. The description adds no parameter-level detail beyond what the schema provides, and does not mention the country weighting behavior or type flexibility, 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 states a specific action ('Resolves up to 100 values in one request') and distinguishes this tool from single-call alternatives by emphasizing bulk usage. However, it does not explicitly name sibling tools like gender_from_name or mention that the bulk call also supports emails and usernames, so differentiation is good but not complete.

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 to use this tool for more than one name and explains that one-call-at-a-time is slower and wasteful. This gives clear context for when to choose the bulk endpoint, though it does not explicitly state 'use the singular sibling tools for one value' or enumerate exclusions.

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