IndexNow: notify Bing/Yandex of changed URLs

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=true. The description adds genuine value beyond annotations by disclosing that 'The tool verifies the key file before submitting', which is an important pre-condition behavior an agent needs to know. No contradiction with annotations; the description's write-implying language matches readOnlyHint=false.

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?

Three dense sentences, each earning its place: core action with limit, prerequisite with location detail, and the Google exclusion. The main action is front-loaded before prerequisites. Slightly packed but not verbose; appropriate length for the information conveyed.

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?

Covers the essentials for an open-world submission tool: what it does, the 1000-URL cap, supported engines, the key-file prerequisite, verification behavior, and the Google exclusion. Missing return-value/response details (no output schema exists), so an agent doesn't know what success or failure looks like. Given moderate complexity (3 params, no nested objects), this is a minor but real gap.

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 67%, so the schema already documents key ('Overrides INDEXNOW_KEY') and keyLocation ('Overrides INDEXNOW_KEY_LOCATION') with descriptions. The description adds context about what INDEXNOW_KEY is and how the key file must be published, which enriches the key/keyLocation semantics. However, the urls parameter gets no extra explanation beyond the schema's uri format, and the description doesn't fully compensate for the 33% coverage gap.

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?

States a specific verb+resource ('Submit up to 1000 changed URLs to IndexNow') with clear scope, and names the target search engines explicitly (Bing, Yandex, Naver, Seznam). The title 'IndexNow: notify Bing/Yandex of changed URLs' aligns with the description, and no sibling tool performs this exact function (gsc_submit_sitemap is Google-specific), so differentiation is not needed.

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?

Explicitly states the prerequisite: 'Requires INDEXNOW_KEY and the key file published at https://<host>/<key>.txt (or set INDEXNOW_KEY_LOCATION)'. Gives a clear when-not signal: 'Google does not support IndexNow', implying the agent should use Google's own tooling for Google URLs. Does not name an explicit alternative sibling tool, but the exclusion is informative enough.

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