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

Annotations already mark the tool as read-only and open-world, so the description does not need to cover those base traits. It adds useful behavioral details: authentication requirement (Bearer key) and cost per successful result. It does not contradict annotations, and the additional context helps the agent anticipate side effects like credential usage and metering.

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 only two sentences and front-loads the core purpose first. Every sentence earns its place: purpose, auth requirement, and credit cost. There is no fluff or repetition.

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?

The description covers the main purpose, required authentication, and cost, which is enough to make a basic call. However, it omits the semantics of the optional max_offers parameter, and with no output schema it gives no hint about the response shape beyond 'EvalResult'. For a two-parameter tool this is a minor but noticeable gap.

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 0%, so the description must compensate for parameter meaning. It clarifies that 'url' must be an HTTPS URL, but it says nothing about the optional 'max_offers' parameter. The agent cannot infer what max_offers controls or how it affects the evaluation.

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 states a specific verb ('Evaluate') and a clear resource ('one HTTPS URL for WebMCP'), which tells the agent what the tool does at a glance. It does not fully define what 'evaluate' produces, but the scope is clear enough for basic selection. Since there are no sibling tools, differentiation is not needed.

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 gives explicit usage context: it operates on a single HTTPS URL, requires a Bearer usr_live_ key, and charges one credit per successful EvalResult. With no sibling tools, alternative routing is unnecessary, but the prerequisites and cost provide clear guidance on when this tool can be used. It doesn't discuss when not to use it, but that is less relevant without alternatives.

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