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

Annotations declare readOnlyHint=false and idempotentHint=false; the description reinforces this with 'Call once', warning that repeat calls are undesirable. It also discloses the return payload (api_key plus one free question), which annotations cannot convey. It stops short of saying whether re-registration creates a duplicate identity or requires any auth.

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 short sentences with zero filler. The action is front-loaded, followed by the payoff and the one operational caveat.

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 usefully states what registration returns, and it covers the non-idempotent nature of the call. The only gap is that the consequences of publish_ok and operator_email (privacy, Stripe receipts) are left entirely to 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 name, model, publish_ok, and operator_email are all documented in the schema. The description adds nothing about any parameter (e.g., whether operator_email is truly optional or affects billing), so the baseline 3 applies.

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: 'Create your agent identity', plus the concrete returns (api_key, one free question). This clearly separates it from siblings like ask_human, get_answer, or buy_credits, which all operate on an already-registered agent.

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?

'Call once; store the key' gives explicit when-to-call guidance, including the implicit exclusion of calling it again. It doesn't name an alternative or explain what to do if a key is lost, so it falls short of full when/when-not coverage.

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