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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely non-obvious behavior: an unknown slug does not error but returns the list of all concept slugs, which changes how an agent should handle failures.

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?

Three tight sentences: the domain model first, then the payoff, then the failure mode. Every sentence earns its place and the most decision-relevant fact (what you get back) is front-loaded.

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?

There is no output schema, but the description enumerates the return shape (question, short answer, explanation, book) and the fallback response, so an agent knows what to expect. A note on slug discovery or related tools would have made it fully self-sufficient.

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?

With one parameter at 100% schema coverage and an inline example ('the-green-lie'), the schema already carries the semantics. The description contributes only the unknown-slug handling, so the baseline 3 is appropriate.

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?

States a specific verb and resource ('Returns the concept's question, short answer, and full explanation with its book') plus the domain model that each book answers one named question. It is clear what the tool retrieves, though it never names siblings like define_term or get_book to disambiguate.

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?

Usage is implied by the concept-per-book framing, and the unknown-slug fallback hints at a discovery pattern, but there is no explicit when-to-use versus alternatives such as define_term or get_book.

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