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

Annotations already declare readOnlyHint=true, openWorldHint=false, and idempotentHint=false, so the safety profile is covered. The description adds only the 'available for purchase' intent, with no disclosure of return behavior, auth needs, or rate limits, so it adds modest value beyond the structured fields.

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 purpose sentence, brief usage clause, and a compact Args line. Slightly redundant (title and first sentence repeat the same idea) and contains a typo ('avaible'), but it is tight and easy to scan.

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?

For a simple one-parameter read-only tool this is close to adequate, but with no output schema the description never explains what the check returns (boolean, status, reason), leaving the agent without a clear picture of the result shape.

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 0%, so the description is the sole documentation for the single parameter. 'pec: the pec address to check' labels the parameter but is essentially a restatement of the field name, adding little semantic detail about format or validity.

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 (checks) and resource (PEC / Certified Email address availability for purchase). The purpose is unambiguous, though it does not explicitly differentiate itself from the check_email_* siblings, which is the main clarity gap.

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?

Explicitly gives a when-to-use condition ('when the user asks if a PEC address is available'). It omits any when-not or alternative-tool routing, but for a narrow single-purpose tool the trigger context is sufficient.

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