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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's job is to add data-shape context, which it does: it discloses that offers are included exhaustively ('every seller offer') and that facts are sourced with links and checked dates. It does not mention error behavior for an unknown slug, but for a read-only detail tool with no output schema this is strong disclosure.

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?

A single front-loaded sentence that leads with scope ('Full facts for one robot') before listing fields. The field list is dense but every clause maps to real returned content; 'what it is' is the only vague item.

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?

With no output schema and one simple parameter, the description carries the return-value burden and discharges it by enumerating the content categories, including provenance metadata. Missing only edge-case behavior, such as what happens when the slug is not found.

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 slug parameter is already documented with its origin (search_robots) and an example (so-101). The description adds nothing about the slug format or lookup behavior, so baseline 3 applies.

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 ('Full facts for one robot') and enumerates exactly what is returned (license, difficulty, build time, cost lines, seller offers, sourced facts). It is clearly distinct from search_robots by being a single-entity detail fetch, but it never names or contrasts with where_to_buy even though 'every seller offer' overlaps that sibling's territory.

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?

No explicit when-to-use, when-not-to-use, or alternative routing appears in the description. An agent must infer that this is a single-robot detail lookup and must go to the schema to learn the slug originates from search_robots. The overlap with where_to_buy is left unresolved.

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