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

Beyond the annotations, the description discloses valuable behavioral details: idempotency across repeated calls, zero credit cost, the exact returned fields (key, key_location, verified), and the user-side requirement to host a UTF-8 file at key_location. This adds significant context beyond the idempotentHint annotation.

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 sentences, each earning its place: the first defines the action, the second lists return values, and the third gives the prerequisite and next step. It is dense but not bloated, with the most important information front-loaded.

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, idempotent provisioning tool with no output schema, the description fully covers what an agent needs: the returned fields, the verified flag's meaning, the user action required, and the follow-up tool to invoke. Nothing critical is missing.

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 input schema has 100% coverage for the single 'domain' parameter, including an example format. The description does not add further semantic detail about the domain parameter beyond what the schema already provides, so the baseline score of 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 opens with a specific verb and resource: 'Get (or create) the IndexNow key for a host,' clearly distinguishing this from sibling tools like submit_indexnow_urls. It also states the key outputs (key, key_location, verified), leaving no ambiguity about the tool's function.

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 clearly situates this tool in a workflow: it must be used before submit_indexnow_urls will work, and instructs the agent to tell the user the location and key then submit. However, it does not explicitly state when not to use it or mention alternative tools, so it falls just short of full exclusion guidance.

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