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

Annotations already declare readOnly=true, idempotent=true, destructive=false, so the safety profile is covered. The description adds real behavioral detail beyond them: scope is limited to the homepage, execution is synchronous and takes a few seconds, and findings carry actionable tips rather than bare pass/fail. It does not cover failure behavior for unreachable sites, but the added context is substantive.

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?

Front-loaded with the core action, then the checklist, then the differentiator (actionable tips) and the speed promise. Every element earns its place, though the long enumerated checklist makes the first sentence dense.

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?

With no output schema, the description appropriately characterizes the return ('each finding includes a concrete tip'), defines scope (homepage-only), and sets timing expectations. Missing only edge-case behavior such as unreachable sites or how results are scoped/limited, which is minor for a single-parameter read tool.

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?

Only one parameter (siteId) and the schema already documents it at 100% coverage ('Site id, from list_sites'). The description contributes nothing further about the parameter, so the baseline of 3 is correct when the schema carries the load.

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?

Specific verb and resource ('fetches the site's homepage and checks on-page technical SEO factors') and it enumerates exactly what is measured (title/meta, canonical, H1, viewport, HTTPS, Open Graph, JSON-LD, alt coverage, indexability, response time). No sibling tool performs an audit, so the agent can distinguish this immediately.

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?

Usage is only implied — an agent infers it audits one site after list_sites. There is no explicit when-to-use, no stated alternatives, and no exclusions (e.g., that it only checks the homepage, not a full crawl, which is set indirectly inside the purpose sentence). The 'no background job needed' remark hints it contrasts with async siblings like get_generation_status but does not name them.

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