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

With no annotations provided, the description fully discloses key behaviors: the new account starts with free credits, the response includes a one-time API key that cannot be retrieved later, and the key must be stored immediately for subsequent use. It also explains domain rejection.

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?

The description is four sentences long, front-loading the primary purpose. It is efficient and covers necessary details without unnecessary repetition. Could be slightly more concise but still effective.

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?

Given no output schema, the description explains return values (account id/email, API key) and usage instructions (capture immediately, use as bearer token). It also mentions free credits and domain rejection, covering all essential context for an agent to use this tool correctly.

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% with descriptions for both parameters, but the description adds meaning: it mentions disposable email rejection (not in schema) and the one-time key generation context. This adds value beyond the 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?

The description clearly states that the tool creates a brand-new Verifly account and is used for self-onboarding. It is distinct from sibling tools (e.g., get_account, verify_email) which serve other purposes.

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 description provides clear context for when to use this tool (agent self-onboarding with no human in the loop) and notes constraints (disposable domains rejected, password min 8 chars). No explicit alternatives are given, but this is the only registration tool among siblings.

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