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

Annotations already declare the safety profile (non-readOnly, non-idempotent, open-world), so the bar is lower. The description adds genuinely useful context beyond them: no credit card is needed and the user will receive a follow-up email, which tells the agent the operation is asynchronous and not self-completing.

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 the outcome front-loaded and the downstream email effect last. Nothing is redundant or padding.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. The description is nearly sufficient, though it never mentions the service parameter (which selects the trial product line), leaving an agent to discover that from the schema.

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 100%, so the schema already documents all seven parameters; baseline is 3. The description names only the four required fields (name, email, company, country) and adds a 'work email' nuance, but omits the service, lang, and notes options.

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+resource — 'Starts the REP27 7-day free trial' — with a qualifier ('no card') that hints at how it differs from create_checkout. It does not explicitly name any sibling, but the free-trial framing is 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?

Usage is implied by the name and the '(no card)' qualifier, which suggests this is the frictionless path relative to a paid checkout, but no explicit when-to-use/when-not condition or alternative is given. An agent can infer context but must guess at prerequisites.

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