read_email

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

Adds real value beyond the readOnlyHint/openWorldHint annotations: it warns that sender-written content arrives wrapped in <untrusted-content> blocks and must be treated as data, not instructions, and it discloses the important side effect that emails are NOT marked as read. It also states the batch ceiling of 10.

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?

Three short sentences, front-loaded with the action and limit, followed by the security warning and the read-state caveat. No filler or repetition of the name.

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 still conveys the return shape ('as the text a person would see', wrapped in untrusted-content blocks) and the read-state behavior, leaving nothing critical unstated for a read-only email fetch.

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%, so both parameters are already documented (UIDs sources, folder default INBOX). The description adds only the batch-size constraint ('up to 10'), which is a minor supplement rather than new per-parameter semantics.

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?

Names a specific verb (read) and resource (emails) plus a hard scope limit ('up to 10 emails by UID'). It implicitly separates itself from the list/search siblings by operating on known UIDs, though it never names those alternatives 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 schema notes UIDs come from list_emails or search_emails, so the workflow (list/search first, then read) is inferable, but the description itself gives no explicit when-to-use or when-not-to-use guidance relative to the sibling tools.

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