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

With no annotations, the description carries the behavioral burden and does so for the most important trait: the tool is paid, and unpaid calls return HTTP 402 at $0.005 USDC on Base, with the full-host alternative at $0.02. It omits any note on rate limits, retry behavior, or what a successful probe yields.

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 short sentences with the core purpose front-loaded and no padding. 'Args domain, protocol' largely restates the schema, a minor redundancy, but nothing is wasted overall.

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?

There is no output schema, so the description would need to explain what a probe returns (detector findings, status, errors) to be complete. It covers cost and the 402 path but says nothing about the success response, leaving a real gap for a two-parameter paid tool.

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 100%, so both parameters are already fully documented, including the complete protocol enum list and domain normalization rules. The description's abbreviated id list ('ucp, mcp, a2a, x402, and the other detector ids') adds no meaning beyond the schema, so the baseline of 3 applies.

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 ('Paid live probe of one protocol') and immediately scopes it against the sibling refresh_host, which handles the whole host. An agent can distinguish this from refresh_host and refresh_hosts_batch without opening a 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?

The contrast 'Full-host refresh_host stays $0.02' implicitly routes the agent: single protocol here, full host there. It gives clear selection context and names the alternative, but never states an explicit when-not condition (e.g. when a full-host refresh is preferable despite cost).

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