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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint. The description goes beyond by explaining error behavior: 'never raises a protocol error — it returns an error object' and that after correcting input it is 'always safe to retry'. This adds critical behavioral context above the annotations.

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 description is well-structured: it opens with the core purpose, then provides an input/output example, usage guidelines, differentiation from sibling, error handling, and safety guarantees. Every sentence adds value, and there is no unnecessary repetition or jargon.

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 single-parameter tool with output schema and clear annotations, the description covers everything needed: purpose, usage context, error recovery, and linkage to list_products for valid slugs. It is complete for an agent to select and invoke the tool correctly without additional information.

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 already states the slug must be exactly as returned by list_products. The description adds a concrete example and clarifies the slug determines which skill is loaded, but does not provide additional semantics beyond what the schema covers. Baseline 3 is appropriate.

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?

The description states it loads a product's free gateway skill with complete instructions, specifying it returns exactly one skill chosen automatically from the slug. It explicitly differentiates from get_full_skill, which handles other skills and requires a paid plan. This provides a specific verb-resource scope and clear sibling distinction.

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?

The description says 'Use when the caller wants usable instructions immediately' and explicitly warns 'Not for the product's other skills: those are named and need get_full_skill with a skill_name, which requires a paid plan.' This gives clear when-to-use and when-not-to-use guidance, along with the alternative tool.

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