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

The description adds meaningful behavioral context beyond the annotations: it stores only domain and labels, never visitor addresses or browsing history, and calling it again for the same domain replaces the existing mapping. This complements the idempotentHint annotation and warns about the overwrite behavior, which is important for an operational setting.

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 three focused sentences, each earning its place: purpose, usage context and permissions, privacy, and overwrite behavior. It is front-loaded with the core action and avoids redundant restatement of the title or schema.

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 three-parameter configuration tool, the description covers the core purpose, the trigger condition, the required permission level, the stored data scope, and the overwrite behavior. No output schema exists, but the description sufficiently explains the effect of the call for an agent to invoke it correctly.

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 description coverage is 100%, so the parameters are already well documented in the schema. The description reinforces that source and channel are short labels and clarifies that only domain and labels are stored, but it does not add substantial new parameter-level meaning beyond what the schema provides.

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 uses a specific verb and resource: configuring how a known external referrer is counted in Arroway's acquisition view. It clearly states the mapping from domain to source and channel, making the tool's purpose unmistakable and distinct from all listed siblings, none of which concern referrer configuration.

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 explicitly says to use it when a product administrator asks to map a domain to a source and channel. It also adds relevant context by noting it is a product-wide operational setting with administrator-only availability, though it does not explicitly mention when not to use it or name alternative tools.

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