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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the returned field set (recipient, subject, status, timestamps), but says nothing about behavior on a missing uid, uid aliasing, or permissions.

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 front-loaded sentence that identifies the lookup key first and the return fields second, with no filler. Only the absence of any routing/qualifier clause keeps it from a 5.

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 one-parameter read tool with annotations covering safety and no output schema, the description supplies the shape of the return value (recipient, subject, status, timestamps), which is the main missing structured information. Error/not-found behavior is the remaining gap.

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 0%, so the description must carry the load; 'by uid' links the single email_uid parameter to its purpose but adds no format or provenance details beyond what the schema pattern already enforces. Minimal but not misleading.

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 (get one transactional email) plus the identifier used to retrieve it, and names the fields returned. It is implicitly distinguishable from mailblaze_list_transactional_emails by 'one ... by uid', though it never names that sibling explicitly.

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?

The 'by uid' phrasing implies this is the single-record lookup versus the list tool, but there is no explicit when-to-use/when-not-to-use guidance and no alternative is named. An agent can infer the split, but must infer it.

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