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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond that by disclosing the response shape and the cap of up to three guides with title, summary and link, which tells the agent to expect a small ranked result set rather than an exhaustive list.

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 purpose and the return contract are front-loaded and the middle sentence carries the scope inventory. The topic enumeration is long but earns its space by defining coverage; a slightly tighter grouping of the list would improve it further.

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 one-parameter read-only search with no output schema, the definition covers what it searches, what it returns and how many results. It does not say what happens on zero matches or whether broad multi-topic queries are supported, which are the remaining small gaps.

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 the single topic parameter is already documented in the schema with an example. The description's restatement ('what the person wants to learn about, in plain words') reinforces that free-form phrasing is acceptable but adds little new syntax or constraint information.

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 (searches) and resource (Moda's published guides) and then enumerates the covered subject areas, which lets an agent tell it apart from search_moda_help or explain_watch_term. It stops short of naming those siblings explicitly, so the differentiation is inferred from the topic list rather than stated.

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 topic inventory: call it when someone wants to learn about watch grades, diamonds, scams, wholesale, etc. There is no explicit when-not guidance and no named alternative for overlapping cases such as looking up a single watch term or general help content.

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