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

With no annotations, the description carries the transparency burden. It goes beyond a simple setter by explaining the implications of each mode (e.g., dealer never sees buyer email in bcc) and the side effect of upgrading the session identity to 'email'. It does not discuss error conditions or overwrite behavior, but the added context is meaningful.

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 concise, front-loaded with the purpose, and efficiently explains the three modes without redundancy. Every sentence contributes useful information.

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 and the lack of an output schema, the description covers the core behavior and mode semantics well. It does not mention return values or failure scenarios, but for a preference-setting tool this is a minor gap, and the available schema provides parameter-level details.

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%, so the baseline is 3. The description adds semantic depth to the 'mode' parameter by explaining the real-world consequences of bcc/cc/none, which is not fully captured in the schema's short descriptions. Other parameters like 'session' and 'email' are straightforward.

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 uses a specific verb and resource: 'Set the buyer's email notification preference for this session' and details three concrete modes. It clearly distinguishes from sibling tools focused on session creation, reading, or messaging by centering on notification configuration.

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 usage context is implied through the description of the action and modes, but there is no explicit statement of when to use this tool versus alternatives or any exclusion criteria. The 'when' is obvious but not directly articulated.

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