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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint. The description adds behavioral context beyond those: free access, no key required, pricing, and a 20-query session limit. It doesn't describe the response contents, but the schema description adds 'public metadata only', and there is no contradiction with annotations.

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 short and front-loaded with the key message, but it repeats the no-key/no-payment point and ends with promotional filler ('Try one of the sample questions now'). It is reasonably compact, though not every sentence earns its place.

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 tool with zero required parameters, no output schema, and strong safety annotations, the description covers authentication, cost, purpose, and sample usage. A description of the exact return format would improve it, but combined with the schema description the tool is sufficiently 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?

Schema description coverage is 100%, so the baseline is 3. The description adds concrete sample questions and names the cvewatch listing, which indirectly informs the question and slug parameters, but it doesn't explicitly explain either parameter beyond what the schema already says.

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 positions this as a free preview of the cvewatch CVE Security Advisories listing and tells the agent to call it immediately. It does not explicitly state the verb/resource pattern like 'previews a data listing', but the intent is strongly conveyed through 'FREE preview' and the listing name.

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 says no API key and no payment are needed, which gives clear context for when to call this tool before authenticated or paid data tools. It does not name alternatives or explicitly state when not to use it, so it stops short of a perfect score.

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