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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, but the description adds real value beyond them: no account/email/PII required, a public unguessable history URL that can be shared, and a rate limit ('a few watches per minute'). The idempotency explanation ('watching an already-watched domain returns the existing watch') restates the annotation but with useful concrete behavior. It stops short of describing failure modes or what the watch record itself contains, keeping it from a 5.

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?

Front-loaded with the core action, then layered with the use case, the follow-on tool, and the operational facts (no PII, shareable URL, rate limit). Dense but every sentence adds a distinct, actionable fact with no filler.

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 no explanation, and the description covers the remaining gaps for a mutating, open-world tool: idempotency, no auth/PII, shareability, and rate limits. An agent has everything needed to decide to call it and how to set expectations.

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% and both parameters (domain, tools) are fully documented in the schema, including enum meanings and the default set. The description reinforces which checks are tracked but largely mirrors the schema's enum documentation rather than adding invocation syntax or format detail, so it sits at the high end of the schema-does-the-work baseline.

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 ('Start (or reuse) a daily DechoNet watch on a domain') and enumerates exactly what is tracked over time (SSL grade/issuer/expiry, DNS, HTTP headers, registration, optional OWASP/impersonation). It distinguishes itself from one-off siblings ('beyond a one-off check') and names domain_changes as the downstream consumer, so an agent can separate it from ssl_check, dns_lookup, etc.

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?

Gives an explicit condition ('Use this once when the user cares about a domain beyond a one-off check') with concrete scenarios (own domain, client, vendor, target under investigation), and identifies the alternative workflow (one-off checks) plus the follow-on tool (domain_changes). Nothing about when-to-use is left to inference.

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