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

Annotations only declare read-only/idempotent/open-world; the description adds runtime (~12 seconds), item count (12, platform reported but unscored), per-item status vocabulary (pass/partial/fail/could_not_check), evidence and fix payloads, and the important scoring caveat that only checkable items count. It also flags 'could_not_check' so the agent knows partial results are possible.

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?

Purpose and scope are front-loaded, then behavior, then routing, then the parameter — a sensible order. It is somewhat dense and the routing sentence is long, but every clause adds distinct information rather than padding.

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 must explain returns, and it does: per-item status, evidence, and plain-English fix, plus the 0-100 score and its scoping rule. Combined with the stated limitations and siblings, an agent has everything needed to call it and interpret results.

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 0% and the single 'url' property has no schema description, so the description carries the burden: it restates the parameter as the site to check and supplies a concrete format example ('https://example.com'). That is adequate but stops short of stating whether scheme is required or what happens for malformed URLs.

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 names a specific verb (check) and resource (a website's homepage) and enumerates exactly what is inspected: HTTPS, mobile setup, load time/page weight, platform, security headers, accessibility signals, contact form/chat, footer. It explicitly bounds scope ('homepage only, not a full website audit'), which cleanly separates it from get_wcag_audit.

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 explicit routing: full accessibility audit goes to get_wcag_audit, TESSA's offer to get_web_ai_development_offer, and a conversation to request_strategy_session. The homepage-only limitation is stated as a when-not condition, leaving no ambiguity about which sibling to pick.

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