IndexNow: notify Bing/Yandex of changed URLs

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

Annotations already provide idempotentHint, openWorldHint, and destructiveHint, so the description adds genuine value by disclosing authentication requirements, the key-file verification step before submission, and the shared-submission behavior across all named participants. It does not cover rate limits or response shape, but the added behavioral context is substantial.

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 with the core action and limit front-loaded, followed by participant context, requirements, and the Google exclusion. Every sentence earns its place, and there is no redundant restating of the 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?

Given no output schema, the description covers prerequisites, protocol limits, participant scope, the key-file verification behavior, and the key Google caveat, which is enough for an agent to invoke the tool correctly. The main omission is what the tool returns on success or failure, but that does not block correct usage.

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 coverage is 100%, so the baseline is 3; the description adds meaning by explaining that a key must exist and be published at a host path, that INDEXNOW_KEY_LOCATION can be used instead, and that URLs are specifically 'changed URLs' for notification purposes. This enriches the schema's terse 'Overrides...' notes.

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 ('Submit'), names the exact resource (IndexNow), states the payload type and limit ('up to 10000 changed URLs'), and enumerates the participating engines. This clearly distinguishes it from the many sitemap/GSC/crawl siblings by identifying the IndexNow protocol and noting Google is excluded.

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?

It gives clear context: use this when you want to notify IndexNow-participating engines of changed URLs, and it gives an explicit when-not ('Google does not support IndexNow'). It also states the prerequisites (INDEXNOW_KEY and a published key file). However, it does not explicitly name a fallback alternative tool, so it stops short of full routing guidance.

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