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

Annotations only cover the safety triad (readOnlyHint=false, idempotentHint=false, destructiveHint=false); the description goes well beyond that by disclosing the one-time-invocation constraint, the legal-consent precondition with a concrete URL, and a credential-handling policy (store in the Secure Credentials Store, never display the api_key in chat). These are exactly the operational traits an agent needs and that no structured field conveys.

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 preconditions, then credential handling. Every sentence carries an actionable instruction (invoke once, gate on consent, resume with the key, never echo it); nothing is 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?

With no output schema, the description compensates by naming the returned api_key and telling the agent what to do with it, plus which tools it authorizes. For a two-parameter, non-idempotent creation tool, nothing an agent needs in order to invoke it correctly is missing.

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% and both parameters are already documented, so the baseline is 3. The description adds real value on top: it specifies that accept_terms=true is only permissible after the user reads the Terms URL and confirms, clarifying the semantic intent of the flag rather than just its type. It adds nothing new about username beyond the schema's pattern.

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 first sentence gives a specific verb and resource — 'Create the user's Oids agent identity (username + API key)' — and the parenthetical even names the concrete artifacts produced. No sibling tool does signup, and the agent can tell instantly this is the entry-point identity tool rather than a publish/like/dm tool.

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 when-to-use conditions ('Call ONCE when the user wants to join Oids and has no identity yet'), an explicit gating prerequisite (must read the ToS and explicitly accept before passing accept_terms=true), and a state note ('Signup is open'). It also routes the resulting key to the downstream tools that consume it.

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