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

Beyond the annotations, it discloses the free/no-plan requirement, the single-skill selection behavior, and a full error contract: no protocol errors, an {"error": ...} object with remediation guidance (e.g. 'unknown slug... Use list_products'), plus retry safety. This is meaningful context an agent could not infer from readOnlyHint/idempotentHint alone.

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 purpose, free status, and return shape before alternatives and error details. The example payload and error verbosity are somewhat redundant with the existing output schema, so it is slightly longer than strictly needed, 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?

Covers the prerequisite (free, no plan), the alternative tool and its paywall, the return shape, and error recovery — everything an agent needs to call it correctly. The presence of an output schema makes the inline return description a convenience rather than a gap.

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 schema already documents the slug and points to list_products, so the baseline is 3. The description adds value with a concrete worked example ({"slug": "brand-voice"} → skill/instructions payload) and by tying the slug to the list_products discovery path in the error text.

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 a product's free gateway skill with its complete instructions') and immediately contrasts it with the sibling get_full_skill, which handles the product's other named skills. An agent can distinguish this from get_full_skill and get_full_product without opening any 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?

Explicitly names the use case ('Use when the caller wants usable instructions immediately') and the exclusion ('Not for the product's other skills... need get_full_skill with a skill_name, which requires a paid plan'). The alternative and the condition selecting it are both spelled out.

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