get_user_by_email

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

The verb 'look up' signals a read-only operation, but with no annotations the description carries the full burden. It does not disclose error behavior, required scopes, rate limits, or what the returned user object contains. It is adequate for a simple lookup but leaves notable gaps.

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 focused sentence with no filler, and the key qualifier 'by their email address' is placed immediately. Every word earns its place.

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 one-parameter read-only lookup with no output schema, the description and schema together are nearly sufficient. Missing return-format and error details would be useful, but the agent has enough to invoke the tool 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?

Schema description coverage is 100% and the parameter is self-explanatory ('Email address to look up'). The tool description adds no additional semantic meaning beyond what the input schema already provides, so the baseline score of 3 applies.

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 ('look up'), a specific resource ('Slack user'), and the lookup key ('email address'). This clearly distinguishes it from sibling user tools like list_users and get_user_info, which operate by different criteria.

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 the tool should be used when you have an email address and need the corresponding Slack user. However, it provides no explicit guidance about when not to use it or which alternative tool to choose, such as get_user_info for ID-based lookups.

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