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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description earns credit for adding behavior beyond that: it specifies exactly what the response contains, which matters because there is no output schema. It does not address error cases such as an unknown id or an ambiguous name match, which keeps it short of a 5.

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?

Two sentences, the payload list front-loaded, no filler or hedging. The enumerated return contents are long but each item carries information; the only minor weakness is that the parameter sentence trails as an afterthought rather than being integrated.

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 single-parameter read tool with no output schema, the description does the essential work by describing the returned structure. Combined with complete annotations and full schema coverage, an agent has enough to call it correctly; only ambiguity/error behavior is unaddressed.

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 parameter already documents both accepted forms (id or name) with examples. The description restates the id-or-name duality without adding format or resolution rules for name matching, so it sits at the baseline for a fully documented 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 opens with a specific verb and resource ("Returns the step-by-step build instructions for one costume idea") and enumerates the payload (decision summary, materials with buy-vs-own tags, numbered steps, safety notes, parent Q&A). That clearly separates it from pick_costume and search_by_owning, though it never names the siblings to make the distinction explicit.

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 rather than stated: the schema reference to "idea id from pick_costume" sketches the natural flow (pick, then fetch the guide), but the description never says when to choose this tool over a search, nor what to do if the user only has a vague costume concept. Adequate but inferential.

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