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

The description adds behavioral context beyond annotations: it clarifies idempotency ('or idempotently return'), states that no tokens are issued (critical), and provides security constraints. Annotations are minimal (readOnlyHint false, etc.), so the description carries the burden well, though it doesn't detail side effects or failure modes.

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?

The description is concise and front-loaded with the primary purpose. It packs a lot of information in three sentences without redundancy. Every sentence adds value, including security warnings.

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?

Given the tool's moderate complexity (one nested object with multiple optional parameters) and no output schema, the description covers the essentials: which parameters are needed per provider, idempotency, token issuance, and security. It could detail what the response looks like, but that's minor. It's complete enough for an agent to call correctly.

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?

The schema description coverage is 100%, so the schema already documents all parameters. The description adds some value by summarizing provider-specific requirements and security notes, but it doesn't go far beyond the schema's own descriptions. Baseline 3 is appropriate.

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 description clearly states the tool creates or idempotently returns an account, which is a specific verb+resource. It differentiates from login by explicitly saying it does not issue tokens and that login should be called afterwards. However, it doesn't explicitly name the sibling 'login' in the same sentence, though it is clear 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?

The description provides explicit when-to-use guidance: it says to call login afterwards for signing in, and it lists which providers are supported, explicitly excluding Passkey/Privy/SSO as out of agent surface. It also gives security guidelines about not logging sensitive data.

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