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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful non-annotation context: the $0.002 USDC price, the x402 payment rails (Base, Solana, Arc), and that failed calls are not charged — material for an agent deciding whether to invoke it.

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?

Three sentences, front-loaded with the core action and the list of weaknesses, then scope limits, then pricing. No redundant or filler wording.

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?

An output schema exists, so return values need not be described. The description covers scope, a key limitation (meta-tag CSP ignored), and payment behavior, leaving little an agent would need to call it 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?

Only one parameter (domain) with 100% schema description coverage, so the schema carries parameter semantics. The description adds no format or edge-case detail about the domain input beyond what the schema already states, matching the baseline-3 expectation.

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?

States a specific verb and resource ('Reads the Content-Security-Policy header of a site's home page') and enumerates exactly what it flags, which is enough detail to distinguish it from the broader security_security_headers sibling without opening either schema.

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?

Provides a useful scope exclusion ('Header only; a CSP in a meta tag is not read'), but gives no explicit when-to-use guidance relative to alternatives such as security_security_headers or security_referrer_policy_audit. Usage is only implied by the narrow topic.

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