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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the description's 'Read-only' restates structured data. What it adds beyond the annotations is the ordering (newest first) and the hard cap of 50 results, which materially affect how an agent interprets and pages the output.

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?

A single compact sentence that front-loads what is returned and the scope, then tacks on ordering, cap and the read-only note. Nothing is redundant or padded.

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 the field list is technically redundant, but the ordering and 50-item cap are behavior the schema alone does not convey. For a zero-parameter read tool this covers everything an agent needs before calling it.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline is 4. The description correctly signals that there is no filtering argument by framing the result as 'the support messages this account has sent' in full.

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 ('the support messages this account has sent') plus the scope restriction to the current account, which an agent cannot infer from the name alone. It also enumerates the returned fields (id, type, subject, source, timestamp), making the tool unambiguous without opening the 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?

Usage is only implied: 'this account has sent' tells the agent it returns the caller's own outbound tickets, so it should not be used when looking for tickets sent to or by other accounts. No explicit when-to-use or when-not-to-use statement is given, though no sibling tool competes for this purpose.

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