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

Adds real behavioral context beyond the annotations: the key is single-display ('shown once'), the achievable scopes are bounded to read/hearts/suggest, and OAuth clients receive no key. Annotations already flag this as a non-idempotent write. It still doesn't mention expiry/rotation of the issued key or any rate limiting, so it stops short of fully transparent.

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?

Short and front-loaded, with the core operation in the first clause. The trailing '[no key]' artifact is unexplained and reads as leftover scaffolding rather than intentional content, slightly hurting polish.

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?

An output schema exists, so return-value detail is unnecessary, and the description still covers the key one-time display, the scope set, and the OAuth no-key path. The main omission is the explicit dependency on request_sign_in having been called for the same email.

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 0%, so the description has to carry parameter meaning. It identifies the code/otp exchange and enumerates the scope values, but adds no syntax, format, or length guidance for email/otp beyond what the names imply. Partial compensation for the coverage gap.

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 transformation: 'Exchange the emailed code for a scoped API key.' The resource (emailed code) and result (scoped key) are unambiguous, and the OAuth-client caveat makes clear this is the non-OAuth completion step of the sign-in flow rather than a general-purpose auth call.

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 scopes the audience: 'for a client without OAuth,' and tells what happens when that condition is not met ('A client already signed in with OAuth gets a short note and no key'). It does not name the counterpart sibling (request_sign_in) as the prerequisite, leaving the sequencing slightly to inference, but the when-to-use condition is clear.

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