User Traits

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive nature. Description adds useful context: case-insensitive matching for 'users' mode and default mode behavior (keys if no key). This goes beyond annotations and clarifies behavior.

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 concise sentences pack all necessary information. Front-loaded with the core action, then details each mode in order. No wasted words.

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?

Description covers all three modes and parameters adequately. No output schema, but the agent can infer return types from mode descriptions. It lacks explicit mention of pagination or result structure, but given the annotations and schema, it is largely complete.

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 100%, but description adds meaning: explains default mode based on key presence and case-insensitivity for value. It clarifies the interaction between mode and key parameters, which is not fully captured in schema descriptions.

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?

Description clearly states the tool's purpose: retrieving user trait keys, values, or finding users by trait. It distinguishes between three modes with specific verbs ('list', 'returns', 'finds'), uniquely identifying its function among sibling tools.

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 explains when to use each mode: 'keys' for listing all keys, 'values' for distinct values when a key is provided, and 'users' for matching key-value pairs. It does not discuss alternatives or when-not-to-use, but the tool is specific enough that the guidance is clear.

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