Check free-certificate eligibility

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description still adds value by stating the required scope (certificates:read) and that the result never exposes provider account IDs, credentials, or private keys, plus that CAs are limited to those operational in the current environment.

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?

Two tight sentences, front-loaded with the core purpose, then the returned facets and the disclosure/permission constraints. No filler 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?

With no output schema, the description carries the burden of describing the response and does so by enumerating the returned fields (eligibility, quota, custody modes, operational CAs). It is complete enough for an agent to call the tool and interpret the result.

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?

Zero parameters, so there is no parameter semantics to clarify; the schema is empty and the description correctly does not invent inputs. Baseline for a parameterless tool 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?

Specific verb+resource (check eligibility for no-cost public DV certificates) with the returned facets enumerated: anti-abuse quota, key-custody modes, and operational public CAs. This distinguishes it clearly from get_free_certificate (which reads an existing cert) and create_free_certificate.

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?

Usage is implied ('check whether this account may request...' reads as a pre-request gate) and the prerequisite 'Requires certificates:read' is stated, but there is no explicit when-to-use/when-not guidance relative to siblings like preflight_free_certificate or create_free_certificate.

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