s3_get_users

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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds that the tool returns service, traffic, and storage usage details, and that full filtering is admin-only, which is useful but minimal. It does not disclose pagination, limits, or error behaviors, but given the simplicity, this is acceptable.

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 a single, concise sentence that front-loads the core purpose. It avoids unnecessary words and conveys the essential information clearly. Every part contributes to understanding the tool.

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 read-only list tool with one optional parameter, the description is largely complete. It specifies the output content (service, traffic, storage) and the admin filter restriction. Without an output schema, a note on response format could be added, but this is not critical 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?

The schema already fully describes the single 'location' parameter with its own description, including the admin restriction. The tool description adds no new parameter details beyond what the schema provides. Since schema coverage is 100%, 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 the tool lists S3 users and includes specific information about service, traffic, and storage usage. It uses the verb 'list' and specifies the resource (S3 users), making its purpose unambiguous. It also distinguishes itself from sibling S3 tools like s3_get_buckets or s3_get_files by focusing on users.

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 that full filtering is available only to administrators, which hints at a usage restriction but does not explicitly state when to use this tool versus other S3 listing tools. There is no mention of alternatives or conditions beyond the admin note. This provides some context but lacks explicit guidance on selection.

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