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

Annotations already cover read-only/idempotent/non-destructive, but the description adds material context beyond them: the PREMIUM license requirement, the no-protocol-error error contract with a concrete example payload, and the explicit 'safe to retry after correcting input' guarantee. It also discloses the return shape even though an output schema exists.

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 core purpose and the alternatives are front-loaded before the example payload. Slightly longer than necessary — the example input/output pair partly duplicates the output schema — but no sentence is filler.

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 two-param read tool with full schema coverage, an output schema, and rich annotations, the description covers everything an agent needs: selection criteria, exclusions, license precondition, and error/retry semantics. 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 description coverage is 100% and both params are documented there with the same examples (slug from list_products, skill_name from the skills array), so the description cannot add much. The inline example input echoes the schema without new format or edge-case guidance, which is the expected baseline-3 outcome.

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 ('Load one paid skill's complete instructions from a product') and names the exact scope (one named skill, selected by skill_name). It explicitly contrasts with get_free_skill and get_full_product, so the agent can route 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?

'Use when the caller wants one specific paid skill' gives the positive selection condition, and the following sentence gives two explicit exclusions mapped to their alternatives (get_free_skill for the free gateway skill, get_full_product for everything at once). This is textbook when/when-not/alternatives guidance.

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