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

Annotations already mark the tool as read-only (readOnlyHint=true) and idempotent (idempotentHint=true). The description reinforces these traits ('Every call is read-only and idempotent') and adds critical behavioral details not in annotations: error handling ('never raises a protocol error — returns an error object with fix guidance'), result cardinality ('returns exactly one skill'), and plan requirement ('no plan required'). No contradictions with 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 with the core purpose in the first sentence, then typical I/O, usage guidance, error handling, and idempotency note. It is front-loaded and every sentence adds value. While it could be slightly trimmed (e.g., 'FREE' is redundant with 'no plan required'), it remains efficient and highly readable. A minor deduction for slight redundancy.

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?

Given the tool has a single parameter fully described in schema, an output schema (not shown but present), and annotations covering behavioral hints, the description covers all essential aspects: purpose, input (slug with example), output shape (slug, skill, instructions), error behavior, usage guidelines, and idempotency. No notable gaps remain.

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% – the slug parameter is well-described in the schema as 'Product slug exactly as returned by list_products'. The description adds value beyond the schema: it shows a typical input/output example ('thesis-advisor' → skill and instructions), explains the source of valid slugs (list_products), and describes error behavior for invalid slugs. This extra context justifies a score above the baseline of 3.

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 clearly states the tool loads a product's free gateway skill with complete instructions, using the verb 'load' and specifying the resource. It differentiates from the sibling get_full_skill by noting this is the free skill with no plan required, and provides a typical input/output example ('thesis-advisor') that clarifies the exact purpose. The scope is specific and unambiguous.

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 states when to use ('when the caller wants usable instructions immediately') and when not to use ('not for the product's other skills'), naming the alternative get_full_skill and the prerequisite of a paid plan. Also notes idempotency and safe retry, giving clear context for invocation.

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