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

Annotations already declare non-read-only, non-idempotent, non-destructive, open-world behavior, so the safety profile is covered. The description adds high-value traits beyond that: the key is shown exactly once, connection_authenticated signals this session is already authenticated, and other connections must send an 'Authorization: Bearer' header.

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, all substantive: what it creates, how the result is consumed, and the no-key alternative path. Front-loaded with the creation fact, though the final sentence about Connect prompts is dense and slightly harder to parse.

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 carries the burden of explaining the response, and it does: the one-time key reveal plus the connection_authenticated field. An agent has everything needed to call this and interpret the result.

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?

Zero parameters, so the baseline is 4. The description confirms 'No arguments,' which matches the empty schema with additionalProperties: false, leaving no ambiguity for the caller.

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?

Names a specific verb and resource ('Creates a zero-credit API key') and specifies the key's nature, which distinguishes it from the billing-oriented sibling create_credit_checkout. It stops short of explicitly naming that sibling, so an agent must infer the boundary from context.

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?

States upfront that no arguments are needed, and explicitly flags the case where the tool is NOT required: OAuth-capable clients get an automatic Connect prompt for paid/account tools, 'so no key is required.' That is a genuine when-not condition, though it is framed as a caveat rather than a decision rule.

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