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

Without annotations, the description carries full responsibility and addresses it well: it outlines the crawl process, the 7 signals checked, scoring, and the 'searchable within a few seconds if the crawl succeeds' caveat. It could add details on failure handling or duplicate submissions, but this is a submission tool with no destructive behavior, so transparency is above average.

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 well-structured sentences: purpose, usage context, and process. Each sentence earns its place, with no redundant text. Key details like the 7 signals are efficiently embedded, making it concise and 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 simple one-parameter tool with no output schema, the description provides sufficient context: what happens on success, the signals checked, and the timing. It could mention what the API returns on failure or success, but the core workflow is well covered. The lack of an output schema raises the burden, but the description still feels reasonably complete.

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 already fully describes the 'url' parameter including format and best practice (homepage). The tool description itself adds no additional semantic information about the parameter. With 100% schema coverage, the baseline is 3, and the description doesn't exceed it.

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 clearly states the tool's purpose with a specific verb ('Submit') and resource ('a URL for NHS to crawl and score'). It distinguishes itself from sibling tools by focusing on adding new sites to the index, while siblings like check_url or get_site_details are for querying or verifying existing entries.

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 provides a usage condition: 'Use when you discover an agent-first tool, API, or service that isn't in the index yet.' This gives clear guidance on when to submit, but it doesn't explicitly state when not to use it or name alternative tools for already-indexed sites. The 'isn't in the index yet' implies the exclusion, and sibling names are available, so a 4 is appropriate.

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