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

The annotations already declare readOnlyHint, idempotentHint, openWorldHint, and non-destructive behavior. The description adds valuable behavioral nuance beyond that: allowlisted host restriction and the fact that a link carrying someone else's code is reported as stale_code even though it may be valid. This helps set expectations for an agent interpreting the result.

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 two sentences with no filler. It front-loads the core purpose, adds a crucial behavioral caveat, and ends with a clear pointer to the alternative tool.

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 single-parameter read-only tool with an output schema and annotations covering safety, the description is complete. It explains scope, edge-case behavior, and when to use a different tool, leaving no key decision unclear.

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 has only one parameter, url, with 100% description coverage. The description does not add further syntax or format guidance beyond the schema, but that is acceptable because the schema already documents the parameter adequately.

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 states a specific verb and resource: it checks whether a URL carries CoinRebate's own current referral code, restricted to allowlisted exchange hosts. It also explicitly distinguishes this from the sibling tool inspect_exchange_link by describing this as a self-check rather than a neutral inspection.

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 gives an explicit alternative with the condition for choosing it: 'For a neutral inspection of any exchange link, use inspect_exchange_link.' This tells the agent exactly when to use this tool versus the sibling.

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