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

Beyond the annotations (idempotentHint: true), the description adds critical behavioral context: it explains that the tool is a complete replacement, notes the monthly edit limit for identity-changing fields, and clarifies that adding precision (e.g., filling a previously null hour) is not counted against the limit. It also states the return value.

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 coherent paragraph, but it contains multiple important points without redundancy. It is front-loaded with the purpose and then details usage rules. While slightly dense, every sentence 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?

Given the tool's complexity (6 required parameters, rate limit, null handling, update procedure), the description is remarkably complete. It covers return value, usage pattern, constraints, and edge cases. No output schema is provided, but the description compensates by stating the return value.

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 input schema already has 100% description coverage for parameters. The description adds value by explaining null handling for unknown fields (e.g., 'hour: null for unknown birth time') and the requirement that minute requires hour to be non-null. This enhances understanding beyond the schema.

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 explicitly states 'Call once to register the user's birth date/time/gender' and clarifies that each call is a complete replacement of all six fields. This clearly distinguishes it from sibling tools like intentions_get_profile, which is used to fetch current values.

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 thorough guidance: it explains when to call, how to handle unknown fields by passing null, the complete replacement requirement, the procedure for updating a single field by merging with fetched profile, and the monthly limit on identity-changing edits. This leaves no ambiguity about usage.

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