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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, but the description adds materially new behavior: a PREMIUM license requirement, and the fact that invalid input never raises a protocol error but returns {"error": ...} with a fix hint. The explicit retry-safety statement after correcting input is exactly the kind of operational context annotations cannot convey.

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?

Purpose and premium status are front-loaded, followed by example, routing exclusions, and error semantics in a logical order. Slightly verbose — the inline JSON example and the return-shape sentence partly duplicate the output schema — but nothing 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?

Two required params at full schema coverage, an output schema covering success shape, and the description still covers the error path and licensing prerequisite. Nothing an agent needs to call this correctly or handle failure 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 coverage is 100%, so the baseline is 3; the description goes further by supplying a concrete example input and output, showing the expected value shapes for slug and skill_name and reinforcing that skill_name selects exactly one skill. It stops short of documenting skill_name matching rules (case sensitivity, aliases), which the schema also omits.

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 scopes it to a single named skill. The final sentence distinguishes it from both get_free_skill and get_full_product, so an agent can route without opening another 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?

Explicit selection rule: 'Use when the caller wants one specific paid skill,' followed by named exclusions ('Not for the free gateway skill, which get_free_skill returns... and not for every skill at once (get_full_product)'). Both alternatives are named with the condition that selects them.

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