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

With no annotations at all, the description carries the full behavior burden. It does earn credit for disclosing a concrete failure mode ("Refuses account-bound models with ACCOUNT_REQUIRED"), which is exactly the kind of error-surface information an agent needs, but says nothing about read-only semantics, auth requirements, or what a not-found slug returns.

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 sentences and roughly twenty words with nothing wasted; the payload enumeration is front-loaded ahead of the refusal condition. Slightly telegraphic phrasing ("the commerce_scope needed to buy") but structurally sound.

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 simple two-parameter detail fetch with no output schema, the description does the useful work of listing the returned fields and one error code. Missing are the identifier semantics and not-found/multi-tenant behavior, which matter given 0% schema description coverage and no annotations.

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 0%: both parameters are bare strings with only a regex pattern and no prose. The description never explains what creator or slug mean, nor that creator is the owning account identifier, so it fails to compensate for the coverage gap on this two-parameter lookup.

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 ("Get a service's") and enumerates the payload returned: functions, inputs, price, purchase model, and commerce_scope. That enumeration implicitly separates it from search_services (discovery) and prepare_purchase (transaction), though no sibling is named explicitly.

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?

Usage is only implied: the required creator+slug pair signals a lookup on an already-known service, and the phrase "commerce_scope needed to buy" hints this precedes prepare_purchase. There is no explicit when-to-use, no statement about when to prefer search_services, and no prerequisite guidance.

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