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

Annotations only declare readOnly/destructive=false; the description adds the required key scope (sites:read), the fixed catalog composition, the returned fields (id, industry, mood, tags, palette, fonts, hero/nav style, forms/CMS collections, pages), and a presentation constraint ('do not show this list raw') — all context the annotations cannot express.

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?

Front-loaded with 'Read-only' and the catalog summary, then the selection rule, then next steps — a logical order. Dense but every clause carries information; the inline field enumeration is the only portion bordering on long.

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?

No output schema exists, and the description fully compensates by listing every returned field plus the layout distinction. Combined with the filter params and annotations, an agent has everything needed to call and use the result.

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 both filter parameters already carry descriptions with examples, so the description only echoes them implicitly ('from the person's industry and the mood words they used'). Baseline 3 applies; no extra syntax or matching semantics are added.

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+resource ('Siteon's starter sites') and enumerates the exact catalog shape (6 industries × 2-3 moods × 2 layouts), then names the two downstream siblings (get_starter, start_from_starter) so the agent can place it in the workflow without opening schemas.

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?

Explicit selection rule: 'Pick one from the person's industry and the mood words they used (or two to let them choose); do not show this list raw.' It also routes forward to get_starter for reading and start_from_starter for building, covering both alternatives.

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