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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. Description adds that 'deep/report tiers add unpaid 402 probing' and lists the public discovery surfaces scanned, giving extra behavioral context without contradicting the 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?

Three sentences with no filler; the most important action and scope are in the first sentence, and costs/tier behavior are succinctly stated in the following sentences.

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?

Given 7 params and an output schema, the description covers purpose, tiers, key parameters, and probe behavior. It omits method/expected details but those are already in the schema; output schema exists so return values don't need description.

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 already describes all 7 parameters (100% coverage), so baseline is 3. Description adds value by grouping optional parameters, linking paid_path to deep/report tiers, and giving per-tier costs, which is semantic context beyond the schema.

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?

Description opens with 'GateCheck readiness' and states the tool 'check whether an x402/agent-facing tool is ready for agent routing, marketplace listing, and paid-path monitoring', naming concrete discovery surfaces like /llms.txt and /mcp. This clearly distinguishes it from sibling scanners/probers by framing it as a readiness gate rather than a direct scan or probe.

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?

It tells the user to 'Pass target plus optional tier, marketplace_url, expected_resources, and paid_path' and defines three tiers with costs. It implies the deep/report tiers are needed when paid-path probing is desired, but it does not explicitly contrast with sibling tools like probe_x402_paid_path or state when not to use it.

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