Search custom domains

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

With Annotations readOnlyHint=true and openWorldHint=true, the safe, read-only nature is already declared. The description adds meaningful behavioral context beyond annotations: it states that the tool searches all custom domains in the account and returns the resource assignment for matches, which is useful for understanding the tool's full reach and result semantics.

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?

A single, well-structured sentence that leads with the action and resource, followed by a clarifying parenthetical. No wasted words or redundant details.

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 tool with one optional parameter and no output schema, the description gives enough context: it clarifies the matching scope and the kind of result ('which resource serves which domain'). The lack of an output schema is partially compensated by the parenthetical. Minor gaps include what happens when no domains are provided, but overall it is sufficiently complete for its simplicity.

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 fully describes the only parameter 'domains' as 'Domain names to match' (100% coverage). The description reinforces this connection but does not add new syntactic or formatting details beyond what the schema provides. The parenthetical is about output behavior, not parameter semantics, so baseline 3 is appropriate.

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 'Match' and identifies the resource 'custom domains' and the scope 'in the account', clearly distinguishing it from sibling tools like list_custom_domains. The parenthetical '(which resource serves which domain)' clarifies the output purpose, leaving no ambiguity.

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 implies a clear usage scenario: when you have domain names and need to find the corresponding serving resource, rather than merely listing all custom domains. However, it does not explicitly mention alternatives or when not to use the tool, so it stops short of a perfect score.

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