loginUser

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

The description adds value beyond annotations by specifying that no session is started, no profile data is returned, and the response envelope is standard BD format. Annotations indicate readOnlyHint, destructiveHint, idempotentHint, which are consistent, and the description fills in behavioral details not captured in annotations.

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 well-structured with bold headings and clear sections, but it repeats the point about no profile data three times. It is relatively concise considering the context, but could be slightly more efficient.

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-parameter login tool with no output schema, the description covers the return format, use case, and next steps. It lacks error handling details but is sufficient for an agent to use correctly. The workflow guidance compensates for missing schema descriptions.

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 0%, so the description carries the burden. It lists required parameters (email, password) and notes they are required, but does not elaborate on their meaning or constraints beyond what the schema format provides. The parameter interaction note about no profile data is helpful but not per-parameter. Adequate but lacks depth.

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 validates user credentials (email/password) and explicitly distinguishes it from related tools by noting it does not return profile data, directing the agent to use getUser instead. The verb 'validate' and resource 'credentials' are specific.

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 provides explicit usage context: 'when implementing SSO or a custom login flow' and clarifies it does not start a web session. It also gives clear after-use guidance to follow with getUser or listUsers, differentiating from sibling tools like verifyToken or createUser.

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