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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes further: it discloses the non-throwing error contract ({"error": ...} with a cause-and-fix message), the retry-safety implication, and the PREMIUM license gating. Minor gap: it does not say whether an unlicensed caller gets a distinct error shape versus an unknown slug.

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 the core purpose and well-ordered (what it does, example, when to use, when not, error contract). One redundant sentence — "Returns persona plus every skill for one product" restates the opening, and the return-shape example duplicates the output schema.

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-param read tool with a full output schema and rich annotations, this leaves nothing an agent needs missing: purpose, alternative routing, license caveat, error semantics, and retry safety are all present.

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 earns extra by showing a concrete call ({"slug": "inbox-assistant"}) and the specific failure message for a bad slug (unknown slug '<value>'), which tells the agent the identifier must match list_products output exactly.

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?

"Load one product in full: its persona plus every paid skill" names a specific verb, resource, and the exact payload returned. It is immediately distinguishable from get_full_skill (one skill), get_free_skill (free tier), and list_products (enumeration).

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 the selection condition ("Use when the caller wants the whole product") and names the two exclusions with the alternatives that cover them: get_full_skill for a single skill and list_products / get_free_skill for a free look. Nothing is left to inference.

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