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

With no annotations provided, the description carries the full burden. It does disclose a key behavioral aspect—that the tool returns the site_key for tracking—but it omits details about side effects (e.g., whether existing sites can be duplicated), required permissions, or error behavior. For a simple create operation, this is adequate but not rich.

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, concise sentence that front-loads the action and the critical return value. Every word earns its place, with no waste or redundancy.

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 simplicity of the tool (2 parameters, no output schema, no annotations), the description covers the essential information: what it does and what it returns. It does not discuss edge cases or constraints, but for this complexity level, it is reasonably complete.

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 already provides 100% coverage with clear descriptions for both parameters ('Human-readable site name' and 'The site's domain'). The description adds no additional parameter-level meaning beyond what the schema gives, so the baseline of 3 applies.

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 action ('Create a new site'), the target resource ('in Measure.events'), and the key output ('Returns the site_key needed for tracking'). It distinguishes itself from sibling tools, which are all read or tracking operations, making the purpose unmistakable.

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?

While it does not explicitly name alternatives or exclusions, the description clearly implies when to use this tool (when a new site is needed) versus the siblings that retrieve data or log events. The context is clear enough for an agent to infer the appropriate usage without further guidance.

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