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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description still adds meaningful context beyond them: the call requires no key and points to an external URL for obtaining one. It stops short of describing what the response actually looks like, which keeps it from a 5.

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?

Front-loaded with what the tool covers, then the trigger condition, then the credential note — a sensible order with no filler. The semicolon-chained phrasing is slightly dense but every clause carries distinct information.

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 zero-parameter, read-only onboarding tool, this covers purpose, trigger condition, auth requirement, and how to get a key. The only gap is that no output schema exists and the description does not state what the returned plan/tool mapping looks like, though it is implied well enough.

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 tool takes zero parameters, so there is nothing to disambiguate and the baseline is 4. The description adds nothing that would be needed here, and nothing is missing.

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 names the concrete content the tool delivers: how to connect a HaterPicks API key, what each plan includes, and which tool requires which plan. That distinguishes it from every sibling (all of which are odds/pricing data tools) without the agent needing to open either schema.

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 gives an explicit trigger: 'Call this first if no key is connected or a tool says it needs one.' That covers both the proactive and reactive invocation cases and implicitly excludes normal data calls, leaving little to inference.

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