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

Goes beyond the annotations by disclosing the error contract: no protocol errors raised, a structured {"error": ...} payload is returned, and retry is always safe after correction, plus a PREMIUM/license signal. The licensing aspect is mentioned but not fully explained (e.g. what happens when unlicensed is left to the generic error shape), 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?

Front-loaded with scope and licensing caveat, then examples, then routing and error behavior. There is minor redundancy between "Returns one named skill, selected by skill_name" and the preceding sentence, but nothing is wasted.

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?

An output schema exists so return values need not be detailed, yet the description still shows a representative response, plus error handling, retry safety, and sibling routing. An agent has everything needed to call this correctly.

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% with both parameters documented, including provenance ("as returned by list_products"), so the baseline is 3. The description's example input conveys shape and value style but adds little semantic detail the schema does not already carry.

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 and resource ("Load one paid skill's complete instructions from a product") and immediately differentiates itself from get_free_skill and get_full_product. An agent can identify the exact scope without opening the schema.

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?

Gives an explicit positive case ("Use when the caller wants one specific paid skill") plus two named exclusions with the sibling that handles each (free gateway skill → get_free_skill, all skills → get_full_product). No inference required.

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