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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds useful context about what the call returns (variants with pricing/availability, rating, review sample), but says nothing about rate limits, auth, or data freshness. Solid but not exhaustive given annotations carry the safety burden.

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, zero waste. The purpose and return contents are front-loaded before the routing guidance to sibling tools.

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?

A single-param read tool with annotations covering safety and an output schema covering returns. The description supplies everything else an agent needs: what it fetches and which sibling to use instead. Nothing material 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 the product_id description already explains the slug format with an example URL. The description only repeats that lookup is 'by product_id', adding no syntax beyond the schema. Baseline 3 is correct when the schema does the heavy lifting.

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?

Specific verb (Fetch) + resource (one Sephora product's details) + enumerated return contents (variants/shades, price, availability, rating, review count, review sample). An agent can immediately tell this from sephora_search or sephora_product_reviews.

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?

Explicitly routes: use sephora_search to find products, sephora_product_reviews for full review pages, sephora_product_questions for Q&A. Names each alternative and the condition that selects it.

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