Lookup Slack User

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

The annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds the return format (list of users with id, name, email, title, status), which is valuable since there is no output schema. However, it does not disclose behavior like rate limits, pagination, or match semantics, so it doesn't fully exceed the annotation baseline.

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 well-structured, with a lead sentence followed by Args and Returns sections. No redundancy or fluff, though the Args section mirrors the schema.

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 search tool with one parameter and no output schema, this description adequately covers purpose, parameter, and return fields. It is self-contained and sufficient for an agent to invoke correctly.

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_description_coverage is 100% and the description's Args section repeats the schema exactly. No additional parameter meaning or usage details are provided, so a baseline score 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 'Search for Slack users by name or email address', providing a specific verb and resource. This distinguishes it from sibling tools like slack_get_user_info, which likely retrieves a single user by ID rather than searching.

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 clearly conveys the intended use case (finding users by name/email) but does not explicitly mention alternatives or exclusions. It lacks a direct comparison to slack_get_user_info for known user IDs, so it earns a 4 rather than 5.

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