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

Beyond the readOnlyHint annotation, the description discloses the exact behavior for both invocation modes: omitting the parameter returns a short list to ask the customer, while passing phong_cach returns a full formula. It also clarifies this is reference data to write better code, not a customer-facing response. No contradiction with 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 short, front-loaded with the key instruction ('TRƯỚC khi viết giao diện'), and uses compact arrow notation to explain modes. Each sentence contributes essential information: purpose, behavior, and a usage caveat. There is no redundancy or filler.

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 read-only lookup tool with one optional parameter and no output schema, the description provides enough information to call it correctly: what it returns in each mode, when to use it, and its role as reference data. No critical context is missing.

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% and already explains that phong_cach is an ID confirmed with the customer and can be left blank to view the list. The tool description adds value by specifying the output difference: a short list vs. a full formula for the given style. This enriches understanding of the parameter's effect 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 clearly states the tool consults TocBien's presentation style library ('Tra thư viện kiểu trình bày') and is meant to be used before writing the interface. It distinguishes itself from the sibling action/deployment tools by emphasizing it provides reference data, not an action. The two modes (empty vs. provided parameter) further clarify its function.

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 states when to use it: 'TRƯỚC khi viết giao diện' (before writing the interface). It also provides a boundary: 'không thay lời khách' (not a substitute for the customer's words), clarifying when not to rely on it. This gives clear context without needing to name sibling alternatives.

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