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

With no annotations, the description itself supplies important behavior: polling is expected, the key is returned only once, and the caller must persist it as FANDUEL_API_KEY. It still leaves pending, denial, expiry, retry, and blocking behavior unspecified.

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 front-load the precondition and action, then provide polling and storage instructions without filler. The awkward and undefined phrase "every interval seconds" slightly reduces precision.

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?

For a one-parameter signup-completion call, the definition covers the main workflow and the especially important one-time credential behavior. Because neither annotations nor an output schema supply additional context, the unresolved polling interval and missing pending/error/expiry semantics remain meaningful invocation gaps.

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 sole device_code parameter is already fully documented by the schema, including its origin in start_signup, and the description adds no further parameter semantics. Its reference to interval has no corresponding parameter or identified source, preventing a higher score.

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 gives a concrete action and resource: collecting the signup API key after email approval, with FANDUEL_API_KEY identifying the credential. Its post-approval sequencing, reinforced by device_code's reference to start_signup, distinguishes it from the signup-initiation sibling.

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?

It explicitly places the call after user approval of the email and instructs polling, providing clear workflow context. It does not explain when to stop polling, name an alternative for checking signup status, or identify where interval comes from.

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