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

With no annotations provided, the description carries the full burden and excels: it reveals the rate limit ('1 audit per IP per 24 hours'), synchronous blocking behavior, lack of auth requirements, and the specific exclusion of Core Web Vitals. These are non-obvious behavioral traits that an agent needs to know before invocation.

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 four sentences, each adding essential information: core function, output summary, rate limit/alternative, and synchronous behavior. It is front-loaded with the action and returns, and contains no filler or repetition of schema details.

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?

Even without an output schema, the description gives a sufficient high-level view of the return content ('scores across 11 modules and ~90 checks, plus actionable findings with rule docs'). It also covers critical operational constraints (rate limit, blocking, no auth, missing Core Web Vitals) and points to the alternative tool, making the description complete for an agent to decide and invoke correctly.

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 schema only defines 'url' as a URI with maxLength, and has 0% description coverage. The description adds meaningful semantic context by requiring the URL to be 'public,' which is not inherent in the URI format. It also implies the URL is the audit target. While minimal, the description compensates reasonably for the single parameter.

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 'Run a one-shot SEO + AI-readability audit on any public URL' with a specific verb and resource, and explicitly distinguishes it from siblings like run_audit (which includes Core Web Vitals and supports API-key volume). It also summarizes the output scope (11 modules, ~90 checks), leaving no ambiguity about the tool's primary function.

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?

Guidance is explicit: the tool is appropriate for anonymous one-shot audits, while 'for higher volume, get an API key... and use run_audit' and 'Does NOT include Core Web Vitals (use run_audit for full PSI scoring)' clearly identify when to choose the sibling tool. This provides direct when-to-use and when-not-to-use context.

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