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

Goes well past the annotations by disclosing that provision and publicKey both return an apiKey shown ONCE and must be saved, and that only the public key is stored (no private key held server-side). This reinforces idempotentHint=false with 'call this once'. It stops short of describing failure behavior, such as what happens if the alias is already taken.

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?

Four short sentences, front-loaded with the purpose, then sequencing, then the parameter choice rule, then the one-time secret warning. No filler and the most actionable constraint (save the apiKey) closes the description.

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?

With no output schema, the description correctly compensates by stating what provision/publicKey return. Sequencing to the auth siblings is covered. What is missing is error/edge handling — alias collisions, existing registrations, or what to do if the apiKey is lost — which matters for a non-idempotent creation call.

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 adds meaning the schema cannot express: the three identity parameters are mutually exclusive modes, and provision/publicKey carry a one-time apiKey return consequence. That mutual-exclusivity rule is genuine added value.

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 — 'Give an AI agent its own @divindi.io email address so it can send and receive email' — which unambiguously separates this creation step from the sibling auth tools (divimail_login, divimail_challenge, divimail_authenticate) and mail tools.

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 says to call this once, then names the exact follow-up path (divimail_login, or divimail_challenge + divimail_authenticate) to obtain a token. It also states the mutually exclusive selection rule across provision/publicKey/nearAccountId with 'Use exactly one of', and ranks them ('provision:true (easiest)').

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