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

Annotations only cover the safety profile (readOnly=false, idempotent=false, destructive=false); the description goes well beyond them by disclosing the returned API key, the one-time e-mail verification requirement, and the exact capability restrictions until verification. This is exactly the behavioral context an agent needs that structured fields do not carry.

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?

Three sentences, front-loaded with the core action and return value, followed by the verification flow and the permission precondition. Dense but each sentence carries information; the middle sentence is long but earns its length.

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 non-idempotent mutation tool with 12 parameters, 42% schema coverage, and no output schema, the behavioral flow is well covered but most parameter semantics are left undocumented. The description is adequate to call the tool correctly but leaves meaningful gaps around the many optional fields.

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 only 42% across 12 parameters, so the description must compensate, and it largely does not. It only implies the email parameter's role; params like kind, operator, countries, categories, key_label, url, city, and phone get no added meaning 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?

States a specific verb and resource ('Creates an account') and adds the key outcome ('returns an API key to store'), which no sibling tool does. An agent can immediately tell this is the account-creation entry point and distinct from update_profile or whoami.

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?

Gives explicit pre-call guidance ('Ask your user for permission and for the e-mail address before calling') and describes the post-call state machine (unverified account can browse and claim/delete min_trust-0 instant tasks one at a time, cannot post). No alternatives are named, but none exist among the siblings, so the guidance is clear for the context.

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