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

Annotations cover the safety profile (readOnlyHint, openWorldHint), and the description adds concrete behavioral context the annotations do not: a per-day quota (3 free calls), an input size cap (500 characters), and the existence of an unlimited paid tier. It still omits what a call returns or what happens when the quota is exhausted.

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?

Two tight sentences with no filler; the primary action is front-loaded and the constraint (size, quota) follows immediately.

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?

There is no output schema, so an agent might want return-value detail, but for a skill-proxy tool the description plus the nested input schema and annotations give enough to invoke it correctly. Quota-exhaustion behavior is the only notable omission.

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, but the description adds a substantive constraint not present in the schema — the 500-character cap on the nested 'input' object — plus the note that input must match the skill's own schema.

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 ('Run a skill once for free') with a clear scoping constraint on input size. It clearly differs from the discovery siblings (find_skills, get_skill, list_recipes), though it never explicitly names an alternative for paid/full invocation.

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 free-tier framing (3 calls/day, 500-char input, 'paid calls have no such limits') implies when to use it — quick trials rather than production runs — but there is no explicit when-to-use statement or named alternative for unlimited execution.

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