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

No annotations provided, so description carries full burden. It discloses that the tool returns an API key, tier, and rate limits; requires name, email, terms acceptance; has a 10-minute cooldown; and may require email verification. It also explains authentication methods. It is transparent about the registration process and limitations.

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 a single paragraph but is well-structured and front-loaded. Every sentence provides necessary information without redundancy. It could be slightly more structured with bullet points, but overall it's efficient.

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 simplicity (3 parameters, no output schema), the description is comprehensive: it explains the key format, authentication, rate limits, cooldown, and what the key unlocks. No missing critical information.

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 covers 100% of parameters with descriptions. The tool description adds extra context: for email, notes that the key may require verification; for terms_accepted, includes the legal URLs. This adds value beyond the schema, earning a score above baseline 3.

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's purpose: 'Get a free Fan Token Intel API key, self-serve — no human in the loop.' It uses a specific verb and resource, and distinguishes itself from sibling tools (which are all other API tools requiring the key).

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 explains when to use the tool (to obtain an API key) and what it unlocks (read-only descriptive data layer, premium metered). It mentions rate limits and cooldown, but does not explicitly list alternative tools or scenarios where this tool should not be used. However, the context is clear that this is a prerequisite for other tools.

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